Linq statement _MyList .Where(c => c.ListItem.Contains(txt.Text)); generates invalid sql like syntax

I am running code like the code below to filter my results in _MyList, this code has ran for ages without any problems but it is now not working for some reason. I had a look at the sql that is being generated and it is building an invalid where clause like this

Result of sql generated from linq code
WHERE [t].[MyColumn] LIKE %12345%


Here is the linq code
_MyList = _MyList .Where(c => c.ListItem.Contains(txt.Text));

Be very grateful for your help.