So, I was hesitant to post a URL because the site is NSFW … BUT!
I think I figured it out (which always seems to be the case when I’m stuck on something … as soon as I post a question about it, I figure it out).
What had happened was … I was using some 3rd party PHP code called detectMobile() to see if the code was running on a phone, and if so, it would leave the tooltip info out. I think this code was working wrong, as that’s the only way that the tooltip info could be missing.
So I got rid of that code, changed it to always put the tooltip on the event, and then just used css to change the tooltip to display:none if it was on mobile.
Now, all of a sudden all of the pictures are showing in the hover tooltips correctly. I just need to wait a week or so to make the problem doesn’t come back.