Hi @Samsung_OaTgZd1, I hope you're doing well.
I believe I may be able to resolve your gallery issue.
This is happening because a ".nomedia" file is present where all your pictures are stored. .nomedia files tell the system not to display media such as images, videos, music, etc... To resolve this, you'll need to simply delete this file.
To delete the ".nomedia" file, follow these instructions:
• Open the My Files app that comes pre-installed on your device.
• Press the menu button on the top right.
• Press "Settings"
• Enable the "Show hidden files" option.
• Go back to the initial page within the My Files app.
• If you know the location of where your images/videos are stored, select either Internal storage or Sd card and navigate to where the media is stored. In this location you'll see a ".nomedia" file at the very top. Press and hold on this file and select the delete option.
• If you do not know where your media is stored, press the search icon on the top right and enter ".nomedia"; you may have multiple .nomedia files. To find the correct one, press and hold on each and press the details button. You'll now have a new window that tells you where this .nomedia file is located.
If you need further assistance, please feel free to let me know.