I thought you used Building Data....why the need to build a fitting? They have just about everything.
You could always see how theirs works, assuming it does and it's not a pattern issue causing them issues too.
Before I submit a ticket to Autodesk, I typically also try their default content to see if the issue exists there. Sometimes, theirs works then I know it's an issue with my config. If it doesn't work in theirs either, then I know it's likely a software issue.
Additionally, when I submit the ticket using their own content, I don't get the "send if your database" push back where they assume it's something I have jacked up.