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variable '__deleted_0' of type 'System.Boolean' referenced from scope '', but it is not defined" in LINQKit

I have some troubles with using LINQKit library in order to include dynamic filters in my queries.
To begin with, I would like to share with a type of filter that is being sent to my query:
public Expression<Func<JobSpecificationDetail,bool>> Criteria { get; set; }
Next, I have my query which simply executes the following piece of code:
var queryTest = applicantCacheRepo
.AsNoTracking()
.Include(a => a.Profile)
.ThenInclude(p => p.ProfileEmployer)
.ThenInclude(p => p.Employer)
.Include(a => a.ProfileApplicationDetail)
.ThenInclude(p => p.ApplicationStatusSysCodeUnique)
.Include(a => a.Person)
.ThenInclude(p => p.PersonDetail)
.Include(a => a.JobSpecification)
.ThenInclude(j => j.JobSpecificationDetail)
.Where(a => filters.ManagerFilter.Invoke(a.Profile)
&& filters.ApplyDateFilter.Invoke(a.ProfileApplicationDetail)
&& filters.StatusDateFilter.Invoke(a.ProfileApplicationDetail)
&& filters.IsTopFilter.Invoke(a.ProfileApplicationDetail)
&& !a.ProfileApplicationDetail.ApplicationStatusSysCodeUnique.Deleted
&& a.Person.Deleted == false
&& a.Profile.Deleted == false
&& a.JobSpecification.JobSpecificationDetail
.Any(jd=>filters.JobSpecificationDetailSpec.Criteria.Invoke(jd)) //this line results in aforementioned exception
&& a.Profile.ProfileTypeSysCodeUniqueId == SysCodeUniqueId.ProfileType.EmployeeApplicant
&& !a.ProfileApplicationDetail.Deleted
).OrderByDescending(a => a.ApplyDate);
So, here in the query, the part which is indicated with a comment, throws that exception. I do not know what to do. In the query, you can find implementation of LINQKit methods as well. They do not create any problems.

C# Entity Framework. Simplify query

How to simplify the next query to database:
public Plan? Get(DateTime now)
{
return context.Plans
.Where(x => IsActivePlan(x, now)) // 1 condition
.Where(x => IsPlolongingPlan(x, now)) // 2 condition
.OrderBy(x => x.StartedAt)
.FirstOrDefault();
}
What I need:
If there are objects after 1 condition, then execute "OrderBy" and return the first element. If there are no objects, then go to the 2 condition, execute "OrderBy" and return "FirstOrDefault". I don't want the objects to be taken at once by two conditions.
Thank you

something like this
public Plan? Get(DateTime now)
{
return context.Plans.Where(x => IsActivePlan(x, now)).OrderBy(x => x.StartedAt).FirstOrDefault()
?? context.Plans.Where(x => IsPlolongingPlan(x, now)).OrderBy(x => x.StartedAt).FirstOrDefault();
}

because you don't want two conditions been true at once you have to:
return context.Plans
.Where(x => (IsActivePlan(x, now) && !IsPlolongingPlan(x, now)) ||
(!IsActivePlan(x, now) && IsPlolongingPlan(x, now)))
.OrderBy(x => x.StartedAt)
.FirstOrDefault();

You can check before if exist any
Like this:
var result = null;
if (context.Plans.Any(x => IsActivePlan(x, now)))
{
result = context.Plans.Where(x => IsActivePlan(x, now))
.OrderBy(x => x.StartedAt)
.FirstOrDefault();
}
else
{
result = context.Plans.Where(x => IsPlolongingPlan(x, now))
.OrderBy(x => x.StartedAt)
.FirstOrDefault();
}

How to include two object inside the same select on Linq MVC5

I do have a complex query to select a full object called Performance
The Performance relationship with others objects is:
Performance has a list of Index
Index has a list of SubIndex
SubIndex has a list of Indicator
Indicator has a list of Item
Item relationship with Spot and Measurement:
Item has one Spot and one Measurement
The query below returns exactly what I want, but I would like to include the Spot and Measurement to the Item object.
return _context.Performance.Include(i => i.Indexes
.Select(s => s.SubIndexes
.Select(d => d.Indicators
.Select(t => t.Items))))
.SingleOrDefault(p => p.Id == id);
I have tried the query below and it is returning the Measurement object. How to include the Spot object?
return _context.Performance.Include(i => i.Indexes
.Select(s => s.SubIndexes
.Select(d => d.Indicators
.Select(t => t.Items.Select(tm => tm.Measurement)))))
.SingleOrDefault(p => p.Id == id);

You could add second Include too;
return _context.Performance.Include(i => i.Indexes
.Select(s => s.SubIndexes
.Select(d => d.Indicators
.Select(t => t.Items.Select(tm => tm.Measurement)))))
.Include(i => i.Indexes
.Select(s => s.SubIndexes
.Select(d => d.Indicators
.Select(t => t.Items.Select(tm => tm.Spot)))))
.SingleOrDefault(p => p.Id == id);

Get parent objects based on child object field value

I need to return all objects that have child objects with a certain field != null.
NOTE: EpicStoryId is nullable int (as in 'int?')
I have tried:
return _context.Features
.Where(x => x.UserStories.Any(us => us.EpicStoryId.HasValue)
&& x.Id == Id)
.FirstOrDefault();
and I have tried:
return _context.Features
.Where(x => x.UserStories.Any(us => us.EpicStoryId != null)
&& x.Id == Id)
.FirstOrDefault();
and for good measure:
return _context.Features
.Where(x => x.UserStories.Any(us => us.EpicStoryId.HasValue == false)
&& x.Id == Id)
.FirstOrDefault();
and finally:
return _context.Features
.Where(x => x.UserStories.Any(us => us.EpicStoryId > 0)
&& x.Id == Id)
.FirstOrDefault();
But none of these work. It's still returning every 'Feature' with Id=Id regardless if a child has a value for EpicStoryId or not. (FYI, I checked the data and there ARE null values for some EpicStoryId's.)
sample data:

Any will return true i any 1 EpicStoryId has value so your your condition is failing.
All should do:-
return _context.Features
.FirstOrDefault(x => x.UserStories.All(us => us.EpicStoryId.HasValue)
&& x.Id == Id);

If you need to return all objects then don't use FirstOrDefault(), use combination of .Where() and .ToList() methods :
For any of us EpicStoryIds are not null use :
return _context.Features
.Where(x => x.Id == Id && x.UserStories.Any(us => us.EpicStoryId.HasValue))
.ToList();
For all of us EpicStoryIds are not null you can use :
return _context.Features
.Where(x => x.Id == Id && x.UserStories.All(us => us.EpicStoryId.HasValue))
.ToList();
If you want to return list of UserStories and not Features, you can use :
return _context.Features
.Where(x => x.Id == Id)
.SelectMany(x => x.UserStories
.Where(us => us.EpicStoryId.HasValue))
.ToList();

EF6 Condition based on sub child

I have this C# code that works, but I'd like to be able to choose the Agency if a person is in it all in the query. Is there a way to do that all in the query?
var retVal = new List<Agency>();
var items=_db.Agencies
.Include(x => x.AgencyMembers.Select(y => y.Person))
.Where(w => w.NationId == User.NationId).ToList();
foreach (var agency in items)
{
if(agency.AgencyMembers.Any(c=>c.Person.Id==personId))
retVal.Add(agency);
}
return retVal;

You should be able to just add that predicate to your query.
return _db.Agencies
.Include(x => x.AgencyMembers.Select(y => y.Person))
.Where(w => w.NationId == User.NationId)
.Where(agency => agency.AgencyMembers.Any(c=>c.Person.Id==personId))
.ToList();
Depending what navigation properties you have, you may be able to simplify it by starting from the person.
return _db.People
.Single(p => p.Id == personId)
.Agencies
.Where(w => w.NationId == User.NationId)
.ToList();

You can try this:
var items=_db.Agencies
.Include(x => x.AgencyMembers.Select(y => y.Person))
.Where(agency=> agency.NationId == User.NationId && agency.AgencyMembers.Any(c=>c.Person.Id==personId))
.ToList();