can't click on photos to enlarge anymore

Great folks at Generatepress - I only just noticed that none of the photos I'm putting up on my newest posts have the clicking capacity to enlarge that they used to have, which many of my photos require if my reader wants to see the detail I talk about. I thought it might be because I'm still on a staging area site, or a pre- vs post-Nikon editor problem I had a few months back. But then I found a post where one photo enlarged and the next one didn't, so I'm clueless. Is it a disturbed link? My WP media library no longer has the 'link to media' option it used to.
I was away from blogging for a few years before returning via Generatepress 6 or so months ago. Is that the norm now, to not enlarge unless a special plugin is used? If so, can you point me to one? I doubt it's a GeneratePress problem or issue, but I'm not getting very current or onpoint answers from forums so far. So if you would point me to where I can go to learn how this issue is handled now, I'd appreciate it.
Thanks in advance. (If y'all ever start up a pay service for support, let us know; I'm in.)
Laura Stella Sitges