Android devices are so varied and there are so many, so we've found many times this could be a device setting.
A couple of thoughts ::
- Did you grant permission to Red Stamp for photos when you downloaded the app? You can alter your settings for all your apps in :: Setttings > Apps + then scroll down your list to find Red Stamp. Give Red Stamp access to Storage and Camera
- Your Photos might have several folders. Please make sure you are checking all your folders.
If this doesn't do the trick, please contact us at firstname.lastname@example.org