Open My Files > Settings > Show Hidden System Files > Locate Pictures Folder > Delete .thumbnails folder.
Dear Samsung Member,
Greetings from Samsung Customer Support!
Please perform the below mentioned steps to resolve the issue:
* Check app cache: Clear cache memory of a particular application: Setting >Apps >Now pick the app. For example 'Samsung Internet' >Storage >Clear Cache.
* Check rebooting your device.
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
Thank you for writing to Samsung.
Samsung Customer Support