Title attribute of images won't save

Everything was working fine until a couple days ago… I had uploaded a bunch of images to a gallery, and edited the titles on half of them, saved fine. A little later, I edited most of the rest, and saved as I was leaving. Came back the next day, and discovered the second batch didn’t take. Tried again, no luck.

Tried editing just a couple at a time, and it worked, but then the next time it didn’t. Kept trying, and every once in a while one or a couple would save, but most of the time they just revert to the filename.

Somewhere in there, I noticed 3.4 was available and upgraded, hoping that would help, but it hasn’t. I’ve tried a different computer and a different browser, but neither makes a difference. Hulp!