Won’t help you that much, but for your info:
I just tested it with the version of Ardour AV Linux comes with (9.8-*), AV-Linux live iso in VirtualBox so with a default Ardour configuration, and it works fine (all three methods).
If it was me i’d backup the ~/.config/ardour9 and try it with a default configuration (and/or with another user).
Perhaps send a screenshot (case seems clear enough, but still).
Good luck.