"View>Flip Horizontal" is grayed out

This issue just started this morning, and for the life of me I can't figure out how to fix it. I have since tried resetting my Photoshop preferences, restarting my computer, and updating Photoshop to 21.2.1, but the problem still persists. So far it's the same across every document I open or create; the "Flip Horizontal" option just seems to be permanently grayed out for me now. I would appreciate any help in regaining access to a feature I use near-constantly.

Thanks,

M.

Edit: upon restarting both my computer and Photoshop once again, the issue has spontaneously resolved itself.