Missing Columns

I have been using the same Creator App for over 6 months. For some reason this morning .. one of my Grid views has no data columns showing at all. It use to have 20 data columns in view. I have not made any modifications in weeks.

When I go into "Edit Application" everything still is the same where all of the Column properties have the "Show" column clicked.

I have tried making some small modifications saving/viewing .. but still the data columns are missing.

Any hints?

-bob