This has been happening intermittently since January – macOS 15.2 & BTT 5.066. It happened again yesterday after the macOS updated to 15.6.1 (currently on BTT 5.536).
I'm not sure if it's every time I restart (which isn't often) and / or only when I restart but the rough pattern I have noticed is that after a restart my BTT global keyboard shortcuts aren't working – at which point I go to click on the menubar icon and get the "wait cursor". In Activity Monitor BTT is "not responding". I force quit it and it respawns, still hanging. The only fix I have found is to force quit it, quickly delete the app, delete the Application Support files (except the licence), download a fresh copy, try to get it into the Applications folder before it automatically starts up – and then reimport my presets from a backup…!
I haven't established if it's related but I also get notifications from Dropbox that I've deleted a lot of .cdeevent files: BTT is tied to a folder "MainStore.v2" in Dropbox, but I can't honestly remember why or how now!
Is there a better fix, or some troubleshooting I should do next time this happens? Thanks.