I thought that inline onebox example worked, but then it didn’t, and then it did again. And it does if you refresh the ‘oops’ page as well. I’ve done a bit of digging and found this existing bug topic on what seems to be the same thing:
The OP in that report renamed their tags to get around the issue, though I’m not sure if they went the manual route or used Replace a string in all posts?
I’ve done a bit of digging and found this existing bug topic on what seems to be the same thing: