Other way round. The submenu that normally shows, fails to show on hover. Simply nothing happens. So it might be visual (it “shows” but is invisible) but I think it’s more likely a logic bug.
No it seems to be an openSUSE issue, and the Flatpak is immune, which is what makes me think it’s about some dependency, but no idea what.
I also have a vague hope it’s connected to the same plugin JSON issue as the bug with the downloader and will be fixed now, but I am flying shortly and won’t have chance to check 
Sadly not going to have time. Screenshot wouldn’t tell you much, it looks literally the same as if the plugin’s menu entry was a normal single command and not a submenu. Locale might be relevant, as sometimes I change it to US English from system to check things. I don’t know if you’ll be able to reproduce it by switching the language?
Ok, that’s reassuring. Was worried it was borked for all Windows 10 users!