I get a read only error message when trying to add a new field to feature classes in a mobile geodatabase ("table or feature class corresponding to this view is read only"). I can edit data within the feature classes, but not the data structure (fields, domains, etc). I also tried creating a new mobile geodatabase in a different folder and copying the offending feature class to it. Still couldn't add a new field.
I'm running ArcGIS Pro 3.1.0. I'm assigned a Basic license currently.
Thanks in advance for any suggestions.