In the lines below, the first line always returns a count and does it for every table.

The second line returns rows for some tables but null data for others (even ones with data and a count returned). The models are all correct and EF and ApplicationDbContext are set up correctly.

I can see nothing else obvious here, can anyone point out what it might be?

var count = _context.RequestLine.Count();
var query = await  _context.RequestLine.ToListAsync();

Error returned:
Data is Null. This method or property cannot be called on Null values.