Can't create a layer mask. The button is greyed out.
Lately, the create mask button on the bottom of the layers panel will be greyed out for me and it won't create a mask, no matter what type of layer I have selected.

The only way I can create a layer mask is by Layer>Layer Mask>Reveal All.
A reboot of Photoshop also fixes it, but it will come back eventually. Is anyone else running into this issue?
I'm on an iMac with macOS Catalina and the most up to date version of PS.
Thanks for your help!
