If you edit small files (500kb) you can save them. For larger files (5MB), the file is not saved. The saving process runs and does not end. There is no error message. But you can’t operate / click anything either.
Seems that the problem only occures using Firefox. With Chrome its working fine.
But after saving and opening the photo again, the viewer does not update the photo and displays the original one. The thumbnail displays the saved (rotated) photo. Opening the photo on mobile app or downloading it also show that the image actually was changed.