If others cannot reproduce the issue, it suggests that more complex circumstances may be involved
By @NetPixel Studio
Cmd/Ctrl+1 for 100% is the same shortcut for InDesign, Illustrator, and Acrobat.
I can think of a couple of things to try, although none may be your actual issue:
Go to Edit > Keyboard Shortcuts and let us know if you are using the default set, a modified default set, or a saved custom set.
Check the keyboard shortcut for actual pixels and tell us what it says. Can you change it there?
Keyboard shortcut sets can be saved with a workspace, so check to see if that is the issue. Your shortcuts may possibly "belong" to one workspace and you are using another.
Sometimes another app takes over PS shortcuts. It could be a browser. Try rebooting and run only Photoshop to see if your shortcut works.
For the Photoshop history:
Cmd/Ctrl+1 used to be the shortcut for the Red Channel. When Creative Suite (not Cloud) first came out, Adobe changed some shortcuts and other things for consistency across applications. Cmd/Ctrl+1 suddenly became 100% to match other applications and Photoshop users emitted screams that could be heard around the world.
The reason I am bringing this up is that if you select the checkbox for "Use Legacy Channel Shortcuts" in the Keyboard Shortcuts dialog, you can still use Ctrl+1 for the Red channel. This probably has nothing to do with your issue, but can you humor me and tell me if that box is checked for you or not? It will take less time than it took to read this paragraph.
Jane
... View more