I’ve noticed this for awhile but haven’t mentioned it.
If you have an existing entity and associated screens and you add a new attribute to the data model in studio a model will appear asking if you would like to add the new attribute to existing screens, and in which fieldgroup you would like to add it.
No matter which field groups you ask studio to add the attributes to on the edit screen, it will always add the attributes to the first available fieldgroup, completely disregarding your choices.
This is very easy to replicate.
This is not a huge deal as you can quickly shuffle things around, but I don’t imagine it is working as designed either.