Bug:
Editing a Grid, there are the (default) displayed fields which are selected using the Edit Fields tool.
There are also the possibly displayed fields which are selected using the Columns tool.
The Fields edit tool should list the fields from the Columns tool (not the Edit Fields) so that these fields can be set up to display correctly (lookups, mostly).
Workaround:
[LIST=1]
Now, when the end-user selects those fields using the Columns button, they will display correctly.
I’d rate this medium to low priority.