Adding Choices field to Backend screen makes list blank

I have a Choices field on Module Builder module.  I would like to show it's value in the backend list when editing the items.  Sitefinity allows me to add it as a field in the Backend screen tweaks editor, but after I do this the content screen for this module is blank.  No error, but the list of module items and the right sidebar are missing.  Only the header of the page remains.  Is this a bug or is there something I can do?  FYI, I'm currently on Sitefinity 9.1.

Thanks...