Hello, Jay Snail
Welcome to Microsoft Community.
The error message indicates that the Ibis Paint lacks authorization to access certain files. Since Ibis Paint was acquired through the Microsoft Store, it is likely that a caching issue with the Microsoft Store has led to permission problems. Have you cleared the Microsoft Store cache? You can do this by pressing Win + R to open the Run window, entering wsreset.exe, and then pressing Enter. Running this command will reset the cache of the Microsoft Store and reopen it.
Additionally, have you tried using the built-in Windows administrator account? This account has extensive permissions. Type cmd in the search bar, right-click on Command Prompt, and selecting "Run as administrator." In the Command Prompt window, type the following command and press Enter:
net user administrator /active:yes
If you want to set a password for the administrator account, type the following command and press Enter:
net user administrator *
You will be prompted to enter and confirm the new password. Log off from your current user account and log in to the administrator account.
Is there any software installed on your computer that might interfere with permissions, such as third-party firewalls or antivirus software? Have you attempted a clean boot? Clean boot starts Windows with a minimal set of drivers and startup programs. It can be used to determine whether a background service or program is causing the permission issue. These steps might look complicated at first glance. However, to avoid any trouble, please follow them in order and step-by-step.
How to perform a clean boot in Windows - Microsoft Support
Has your Windows been updated to the latest version? Have you considered uninstalling and reinstalling Ibis Paint?
Lastly, have you used the System File Checker to check for any damaged or missing system files?
How to use System File Checker in Windows - Microsoft Support
Yuhao L
Microsoft Community Technical Support