I was adjusting field labels within Project Entities. Changed the label for BG_SUBJECT from "Subject" to "Project / Functionality". Now, although the underlying data is still in place in the database, grid display of the Subject field is blank and is only filterable as text (previously was filterable as a select tree).
Also, opening defect details window results in an error dialog "Cannot convert the given value to the given type. The type <__ComObject> is not supported."
Lookup in BUG table shows integer data for BG_SUBJECT field as would be expected, but it's not pulling in the actual data.