I have also had problems in Audacity that I posted here: https://iplug2.discourse.group/t/has-anyone-tried-their-plugins-on-audacity-3-6-i-seem-to-have-problem/927
Reaper is a great development host because it loads fast. But I have also found it extremely robust - it will load plugins that crash or fail in some way in other DAWs. So it is not a great test host, IME.
I have had AU plugins pass Logic’s AU validation but still fail or crash when loaded in a project.
What I have trouble understanding is if all of these plugin types (VST, VST3, AU, etc) are “standards” why does a plugin work in some DAWs but not others?
So my approach has been to try my plugins in as many DAWs as possible and get VERY comfortable with the debugger!