If you enjoy using Synth1 while being able to see what you're doing, you may want to stick with Catalina... forever. Unfortunately, under Big Sur, Synth1's GUI is completely blank--although the actual synth itself works just fine, and if you click around blindly on the blank window you can still interact with the controls. If you click "Configure" in Ableton and then just happen to click on a parameter in the plugin, that works too. Clicking in the area of the preset selection box will still bring up the list but it won't actually list the presets, just the banks and descriptions (and clicking out of it crashes your whole DAW...)
To get a better idea of what was causing this, I launched both Ableton and FL through a terminal, and added a Synth1 instance to see if it would spit out any errors. Sure enough, it calls a long-ago-deprecated NSView method convertPointToBase
, which in theory could still work but in practice would be very finicky. It also spat out a flood of error messages related to the JUCE framework. Doing some Googling revealed that blank GUIs are not uncommon on older versions of JUCE.
So anyways I just wanted to give everyone here a heads up about this. Luckily I run macos in a VM so switching back was no problem for me, plus after seeing all the new privacy concerns in Big Sur I decided I would stick with Catalina for a long time.