>Hi,
>A further update to the problem, it appears that any Filter set in the DE throws the error. Setting Filter to .F. also
>throws the error.

Do you get an error with this code, or does it just ignore the filter?

CREATE FORM FilterTest NOWAIT
ASELOBJ(laForm, 1)
loForm = laForm(1)
loForm.AddObject("Grid1", "Grid")
loForm.Grid1.Visible = .T.

ASELOBJ(laForm, 2)
loDE = laForm(1)
loDE.AddObject("Customer", "Cursor")
WITH loDE.Customer
	.Database = HOME(2) + "data\testdata.dbc"
	.CursorSource = "customer"
	.Alias = "customer"
	.Filter = "cust_id = 'ALFKI'"
ENDWITH

KEYBOARD '{ENTER}'
DO FORM FilterTest