Step 1: iPhone 15 Pro photos are causing the “creating observation” step in iNat Classic and iNat App for iPhone to load indefinitely. Other file types such as .jpeg taken by another camera and screenshots work fine for creating observations
Step 2: I redownloaded the iNaturalist iPhone app and that did not solve the issue.
This is probably due to the HEIC image format that iPhones use natively. Go to Settings > Apps > Photos, and down at the bottom under “Transfer to Mac or PC” check “Automatic”. That should convert it to jpeg whenever you transfer it off your phone.
You may want to change your iphone camera format to “most compatible” under settings, this will change the format from HEIC to jpeg. iNat isn’t the only platform that struggles with HEICs, definitely worth making the switch.
I believe that any RAW file in the iOS or MacOS photos apps automatically also get saved as a jpeg (or maybe heic on mobile devices) for displaying them.