Select all keyboard shortcut (CTRL-A) suddenly stopped working; rest still work

So this is super bizarre and I'm not even sure where to post, but suddenly my CTRL-A keyboard shortcut no longer selects all on any application. The others still work (CTRL-C, CTRL-V, CTRL-Z, ect), just CTRL-A is not working. I'm using Win10 with a Das Keyboard. I do have the keyboard running to the built-in KVM in the Gigabyte M32Q monitor, but I don't think that's it as the other shortcuts work. I'm can't figure out why just the one shortcut would stop working... is there a registry entry I need to check or something?

Thanks all!

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