I tested in 15.2 on macOS 12.6.3 with a 15-pixel outside border in a new document and I don't see the issue.
I haven't seen other reports of this at this point.
Please include the exact parameters so we can try to reproduce it.
Perhaps updating the OS and testing in a new document would clear it up.
Thanks Craig. I did try it in a new document and the border creation was fine. So then I tried it in a new shot in my existing document and I was also able to get a border. So then I tried again in my original shot and added a new camera source and once again I was able to add it properly.
It must not like my sources in the original shots I have setup so I'll alter those and everything should be good. Thanks for checking this out yourself.