- Quit the app and relaunch
- Power off then on the iPhone
- Delete app and reinstall (no problem if in-app gallery not included)
After finding no problems on the iPad Pro, and looking at my All Photos collection - I see that my most recent photos were shot in RAW format. Other Albums with JPEG, HEIF and TIF files display and load as expected.
Thanks for checking on this problem (where I stumbled over my own feet) and confirming that your iPhone and IB are working as expected! I've also added a complimentary review for IB on the App Store.