Hi...
I just tried and Photopea and it opened up fine for me. Do you still have the same issue?
If so, it would be worth uninstalling the Photopea plug-in using the Reallusion Hub and then reinstall it (make sure CTA4 is closed down). Does this resolve the problem?
And if you are using the Windows version of CTA4, please try right clicking the CTA4 desktop icon and choose "Run As Administrator" when launching CTA4 to see if this helps.
Peter
Forum Administrator
www.reallusion.com