I’m using MDFFS v1.2.29.0. When creating a dropdown field that uses a REST filter (eg, a second level in a cascading dropdown) if I set the “Allow invalid values” choice to Yes, the form will initially render when I load it, and then goes blank after about 1 second.
I’ve confirmed it on two separate fields on my list. For my own reminder, the list is called TOGAF Application Portfolio Catalog, and it is happening on the CB Segment field and the WF LOB field.