Alright so I've tried uninstalling the Magisk app, reinstalling it, wiping the app data, rebooting, installing again and so on. The Magisk app with run again when I do that stuff, but when I try to hide it, it clocks and clocks and creates another Manager app without the name I've specified and without an icon. The one with the Magisk logo is also still showing too, so then I'm seeing two apps.
For the love of.... nothing is fixing this.
1. Turned on airplane mode
2. Force closed Magisk app, wiped data, uninstalled
3. Booted to bootloader, flashed factory image w/ -w flag removed to avoid wiping data
4. Booted system, noticed somehow there was still a Magisk app that had re-appeared. Repeated step 2.
5. Booted to TWRP image and flashed TWRP
6. Booted system, then back to the now-flashed TWRP and flashed the Magisk 21.4 zip
7. Booted system, and the Magisk app was back - repeated step 2
8. Installed Magisk Manager 8.0.7 apk, opened it and checked Magisk Hide apps -- all the ones I previously had checked were still there.
Whatever the hell happened broke the hell out of Magisk Manager, and I have had no luck trying to find where it's kept with a file manager. If I did, I would delete it all and just start over, but at this point I cannot afford to do a full data-delete-factory-reset, so I'm screwed.
If anyone knows where the heck Magisk stashes it's data, please let me know so I can manually delete it all and install it fresh. I thought this stuff wasn't supposed to happen on the "Stable" channel...