Hello @Scotty73,
Have you tried clearing app cache? You can find it under Settings > Apps > select the app > Storage > Clear cache. You can also check the app permissions and make sure the app has access to all of your photos and not just selected ones.
Also please keep in mind, that during the One UI Beta, it is possible that not all third-party applications will work as expected, due to compatibility issues 😔
Have a good day!
P.S. Very cool beagle profile pic 
