A web app I use uses Ctrl+Shift+0 through 9 as particular keyboard shortcuts. Ctrl+Shift+0 has never worked for me, but 1-9 always did. I rarely had to use 0, so I just sort of ignored it. However, suddenly Ctrl+Shift+1, +3, and +8 have also stopped working - possibly right after upgrading to the latest version of Windows 10; I'm not exactly sure on the timing of when I updated and started noticing this behavior. This is happening across multiple browsers, and it's not the app itself that's having issues as going to keycode.info and checking to see which key presses are being registered confirms that those four specific number keys are not being registered when Ctrl+Shift are also being held down.
I also doubt it's a hardware issue as I used AutoHotkey to map that specific sequence to my function keys and I'm getting the exact same behavior as when actually physically pressing all three keys. It seems like Windows itself must be overriding that key sequence or something, but I can't figure it out.