That’s apparently a known issue, which could be fixed by building QGC yourself, but I’ve also asked internally if there’s some way to get an image available (I haven’t yet had a response). That said, we only actively support the latest stable version of operating systems (e.g. Ubuntu 20.04), so it’s possible we won’t be able to spend time/resources on sorting this out for you.
Good that it works correctly/as expected in 4.0.x. 4.2.0 isn’t a version we’ve tested extensively yet, and it’s not the version we recommend. I’ve asked previously whether we should move to 4.2 but was told at the time that it likely requires some changes before we can recommend it.
If possible, you may need to stay on 4.0.5 for now, or try building 4.1.4.