PredicateBuilder producing incorrect SQL statements

Question

So I'm using LINQKIT found here

And I'm trying to create an expression on one of my columns, CID.

The predicate looks like this:

Dim cid As String = "11R"

Dim predicate = PredicateBuilder.[New](Of uv_Manifest).And(Function(x) x.CID = cid)

And it returns a predicate which looks like this:

{x => (CompareString(x.CID, value(FSVendor_RefactoredRepository.ManifestManager+_Closure$__2-0).$VB$Local_cid, False) == 0)}

This returns SQL which looks like this:

SELECT 
    [Extent1].[CID] AS [CID], 
    FROM (SELECT 
    [uv_Manifest].[CID] AS [CID],   
    FROM [dbo].[uv_Manifest] AS [uv_Manifest]) AS [Extent1]
    WHERE ([Extent1].[CID] = @p__linq__0) OR (([Extent1].[CID] IS NULL) AND (@p__linq__0 IS NULL))

When I run this statement in visual studio it times out, whereas if I hardcode the predicate to be like this:

Dim predicate = PredicateBuilder.[New](Of uv_Manifest).And(Function(x) x.CID = "11R")

It works fine and gives me a predicate which looks like this:

{x => (CompareString(x.CID, "11R", False) == 0)}

And the SQL looks like this:

SELECT 
    [Extent1].[CID] AS [CID]
    FROM (SELECT 
    [uv_Manifest].[CID] AS [CID]
    FROM [dbo].[uv_Manifest] AS [uv_Manifest]) AS [Extent1]
    WHERE '11R' = [Extent1].[CID]

And it executes fine.

Here is my line of LINQ:

Dim q = webDataContext.uv_Manifest.AsExpandable().Where(filters)

Why is it when I change the value to be hardcoded it works as expected but when I don't it doesn't create the correct SQL statement and how do I fix this?