Elements 15 caption edits not visible in Window Explorer

I've just made the leap from Elements 12 to Elements 15, and along the way apparently lost the ability to edit captions and then view them through Windows Explorer (Windows 7). (Captions assigned from scratch with PSE 15 are still immediately visible in Explorer, but not captions I've just changed.)

I have massive numbers of photos I captioned with PSE12, and need to change quite a bunch. I can load the JPEGs into Organizer, select a bunch, then select "Add Captions to Selected Items" and type the revised caption (whether or not I check the "Replace Existing Captions" box makes no difference). The new caption is visible in PSE15, and I can see it if I use an EXIF extractor, so I know the actual metadata is just fine. But I cannot view the caption in Windows Explorer (right-click on file name, select "Properties", then select "Details," and view the old caption under both "Title" and "Subject").

Again, when I was using PSE12,  I changed captions all the time, for single images or bunches of images, and could immediately see the revised caption in Windows Explorer.

Anybody got any ideas what wrong? This is a big problem for me (changing captions one at a time with Explorer is a very big job when you're talking about hundreds or thousands of images). Just for the heck of it, I've tried closing down everying in PSE 15 and starting over with caption edits. Nothing. I've closed Windows Explorer and reopened it. Nothing. I've done the whole reboot routine and, again, nothing.

And, just to repeat myself, I'm following the exact same caption editing steps that worked just fine in PSE 12, so the problem ain't me.