Graphics driver did not help. No idea what's going on.

Does the same happen with the History "Ctrl+Shift+H" shortcut?

You can try "Clear the startup cache..." in "Help -> More Troubleshooting Information" (about:support).

• https://support.mozilla.org/en-US/kb/use-troubleshooting-information-page-fix-firefox

History opens just fine! That's a great workaround for now! Bookmarks manager still doesn't work after clearing the startup cache. Also didn't mention in my original post but the shortcut doesn't work in safe mode either.

You do use the en-US locale? Do you see this "Ctrl+Shift+O" shortcut ('O' as in Organizer) listed in the Bookmarks menu (Alt+B)?

Yes, I use English, and it shows the correct shortcut in the bookmarks menu.

I received a reply on email that isn't visible on this thread, but I also confirmed the Ctrl-Shift-B to open/close the bookmarks bar is working normally, and I tried running a firefox installer again to clear corrupt files and that did not help either.

Reboot the computer into Windows Safe Mode with network support to see if that has effect.

• https://www.bleepingcomputer.com/tuto.../how-to-start-windows-in-safe-mode/
• https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/

The email about a reply you received looks like generated via AI and has a spam link and has been hidden by a moderator.

Thanks cor-el, that did indeed restore the shortcut function. I was very confused why this would help with exclusively this hotkey and not affect anything else.

That let to me doing an exhaustive study of all applications that run in my user space on startup to see which ones have keyboard shortcuts.

Despite not having a startup entry or task tray icon, I discovered a running application called "AMD Software: Host Application" running on my system. I believe this was installed a couple months ago as part of a driver update, quite possibly with the MSI motherboard's drivers.

Bizarrely, by default the app only used L, K, and F11 for hotkey bindings, but I can confirm that disabling the hotkey feature entirely immediately allowed me to open my bookmarks again.

I can only conclude that there is something wrong with the AMD software that is causing it to capture more hotkeys than programmed for. It appears that others are experiencing this issue as well: https://community.amd.com/t5/pc-drivers-software/amd-adrenalin-is-stealing-keyboard-shortcuts-and-breaking-almost/td-p/667591

I appreciate the help!

...I discovered a running application called "AMD Software: Host Application" running on my system...

I'm setting up a new AMD system, and discovered the same problem with the Firefox bookmarks shortcut. THANK YOU for taking the time to post your findings, this saved me a lot of hassle!