"Insert Pictures" grayed out?

Hi all-

I am an experienced Word user, but this issue has me baffled. I obviously inserted a photo in my document (saved as a docx) a few days ago (see attached image), but now the the insert pictures button is grayed out. The problem is not with just this document; others I've opened this morning have the same issue. I was unable to locate a solution with web searches. Very odd!
Thanks!