Since upgrading to iOS 11, my phone captures photos as HEIFs. I have an older iPad that has reached its update limit at iOS 9.3.5. It supports iCloud Photo Library, and I have that turned on.
All of my older JPG photos show up just fine, as you'd expect. But the new ones behave strangely. Here's what I see in the Moments pane:
If I tap a photo, it initially opens as a large version of the JPG placeholder. If I wait a moment, sometimes the full version of the photo appears, with an exclamation point in a circle at the bottom. I assume this has something to do with it being an HEIF converted to a JPG, but it does nothing when I tap it and there is no other indication of a problem.
Loading the photos individually does not fix the grid view. I've tried restarting the iPad, restarting iCloud Photo Sharing, signing in and out of iCloud, and letting it sit idle for an inordinate amount of time in the hope that the thumbnails would load. They do not.
I know that one solution is to stop using HEIF on my other devices, but I am hoping to avoid that.
How can I get the thumbnail view to work and the individual images to display reliably?