Split Staff From Parts Creates Unusuable Staff

1. Create a staff, put some notes on it.
2. Create a part.
3. Navigate to the part.
4. Split the staff
5. Observe that the newly created staff is unusable. If notes were in the staff below the split point, they will be in the staff. If there were no notes below the split point, that part of the new staff will contain nothing, and cannot be interacted with.

The workaround is to split the staffs from the score part, and delete & recreate every single part, but one will lose all customized formatting (line breaks, page breaks, adjusted positioning, probably more) in the process.