I retested this with "Ubuntu Software" (/snap/bin/snap-store) which seems be the replacement for the software-center and it installed the test package without trouble.
So if the software-center is indeed deprecated and not in use anymore this bug can be closed.
I retested this with "Ubuntu Software" (/snap/ bin/snap- store) which seems be the replacement for the software-center and it installed the test package without trouble.
So if the software-center is indeed deprecated and not in use anymore this bug can be closed.