[IGN-2416] 8.1.4-RC1 Can't change parent data type of non-nested UDT instance

Looking at the forum post regarding the original issue, it looks like what you are seeing is expected.

I'll go ahead and write up a new issue to fix this since it sounds like a lot of our reasoning behind the change was focused on nested instances. Regarding issues like this, while the forums have active IA employee presence it's not officially a supported way to report bugs to us so there's no guarantee anyone sees these posts.