When using spff to poplulate a lookup field where the lookup list have a large number of items spff does not work. Lets say I have a an item in the lookup list called "Customer A" when using "?Customer=Customer A" the field is correctly
populated with the string "Customer A", but when I save the item the field is not set.
Also if I use "?Customer=Non existing value", the field is populated with that string even though that item does not exist.
I use SharePoint 2010 and all the other field types seems to work flawlessly, but I really need to be able to poplulate lookup field :)