I upgraded my Macbook Air to Catalina and all went well on the install, you do get lots of messages asking if you want some apps to be able to access certain areas though. This I guess is the extra layers of security Apple has built in, and probably why some apps need updating, not counting the 32 bit ones. I do have a copy of BiaB 2019 on the Air which works fine except for the Amplitube RealTracks, which I expected. I am leaving the update to Catalina on my iMac until IK and Native Instruments get things sorted.

Tim