Running a pretty standard Ubuntu Studio 21.04 install here, with Jack for audio. Rack 2.0.4 works well overall; haven’t upgraded to 2.0.5 because of the sample rate issue some users pointed out (details here). Performance is improved compared to Rack 1.6. Haven’t experienced anything like that volume bug described by @Soxsa – sorry. Main problem I’ve encountered is MIDI input causing crashes – someone on Discord told me it’s a known bug, I emailed support with details in case it might help. I agree that using version 1 is safest if you want to be sure you can rely on the software. Fixes have been coming pretty quickly, so I’m hoping Rack 2 will be stable soon. I’ve run some good patches in it so far.
@contemporaryinsanity Are you running Rack 2? I had that problem with the dialogs in Rack 1.6, but Rack 2 solved it (once I installed the Zenity package, which really should be listed in the system requirements). In the KDE system settings for Window Behavior, I have “focus stealing prevention” set to medium.