Typed trigger suddenly stopped working for all macros.
I've reset all accessibility permissions, disabled/enabled groups, created new groups and fresh test macros to trigger, restarted the computer, and re-installed Keyboard Maestro.
The "settings" within the Typed Trigger also don't change anything. ("case does not matter" etc.)
Does anyone have any idea what else I could troubleshoot? 
You didn't do anything wrong, but the first thing you should always do is check the Engine log to see if the macros are firing. That's because the phrase "not working" doesn't really tell us if the macro is firing or not. (Your macro could be exiting rather than not starting.) Alternatively, you could also turn on the debugger with "Pause New Macros" checked, and see if the macros are triggering that way. There is also an option under the Help Menu called Interactive Help which is designed to help with things like this (but I confess I've never used it.)
Any time a macro “does nothing”, start by selecting the Interactive Help, Something expected is not happening, and see what you can learn.
It may be that the macro group is inactive or disabled for example.
There are also debug settings that can be turned on to show what is happening with the Typed String trigger buffer if that does not help.