Hi, Kalia:
Here are some suggestions that I hope work with your problem:
- You can only set a photo as a home screen wallpaper if your photo is a normal photo or Live Photo. Currently I haven't heard of other photo format that supports setting-as-a-wallpaper feature.
- Try relaunching Settings App & Photos App. You have to first go back to the home screen, then open the app switcher, and swipe up the app to completely shut down the app. Reopen it to see if anything changes.
- Check if your photo size is too small. Although the wallpaper feature supports all sizes, but I think the best size that fits is more than a million pixels (I'm not sure about this one).
- Restart your phone.
- Try turning off features that connects with display, such as True Tone and Dark Mode because changing wallpaper may occur small conflict with them.
If the problem still exists, please tell me, and send a screenshot in the community if possible.