Why is Mark Face sometimes grayed out in the Elements Organizer 2020 lower ribbon?

 @Newmountain said: I've also noticed that, if the program recognizes a face and asks "Is this (Jane Doe)?" and I hit the x button indicating that it's not that person, the program doens't respond right away. I can hit the x several times and it still keeps asking the same question, but if I wait anywhere from several seconds to several minutes, it finally accepts that it's the wrong person and asks me to add the name.

That is a known issue.  But, as I said, I have never seen the greyed out Mark Face button mentioned before. 

Personally, I tend to use the UnNamed People tab to  identify faces.  There really is no reason (for me) to see a marked face in a stack.  So, my only suggestion would be to simply click and drag a People tag to the image.  This will allow you to use the search mechanisms to find images of that person even though there will only be a generic icon for the face in the People stacks.

I've never seen this problem before.  I'm wondering whether there is a process that is happening in the background that is interfering with the Mark Face feature.  For example, if this is happening after a recent import of photos, there could be some media analysis taking place that is temporarily interfering.  I say this because the faces in your photo should be recognized automatically.  Do you have People Recognition turned on in the View menu?  Has Face Recognition been completed on your image?

To test my theory, try going to Edit>Preferences>Media-Analysis and uncheck all of the boxes.  Reboot and see whether the problem continues to occur.

Are you in Full Screen View for the photo you want to mark? 

The only time that the Mark Face is greyed out for me in FSV is if I have a video selected.  Are you possibly trying to mark a face in a Live Photo from an iPhone?

Please show us a screenshot of the Mark Face button being greyed out for you.

Added:  And since the button does work if you leave and return to the image, this may simply be a computer resources issue.  What are the specs of your computer and monitor?