I have included a list of things to check that may solve this issue. You can also export your files with other methods here: https://float.support/article/9000205854
Please note that you can always easily save all your files to a Mac or PC, here’s how: How to export all Locker files to Mac or PC
Things to check:
- Go to Settings app > Locker > Photos and make sure you have allowed Photos permissions access
- Go to Settings app > Storage and make sure your storage is not too full
- If you were trying to save photos to your photos app, instead do “Export All Files” from the Locker menu, save to your Files app, then go to your files app and save back to photos app from there.
You can also export files individually by holding down on them and choosing "Send / Share".