App Switcher not working when Logic Pro is in focus

Anyone else experienced this? I'm on Catalina, and all of a sudden, the App Switcher (cmd+tab) no longer responds while Logic is in focus. It works fine with every other app. Very very odd. I've tried initializing all key commands in case somehow the same key command had been added as a Logic shortcut, but no change.

I uninstalled Logic with Appcleaner to remove all preferences and associated files and even reinstalled the OS, and still the App Switcher isn't playing ball. Also, I noticed that when the App Switcher does work (when LP isn't in focus), the switcher appears on my MBP's internal screen, whereas it used to appear on my main external monitor.

Any help massively appreciated as it's driving me a bit nuts!