It is not possible to open 'PCP > System > Settngs > Brands' menu neither from branding UI nor from MN UI. The load usually fails in 5 minutes.
Transaction timeout is not enough to handle the volume of domains on provider level during the page load.
Caused by the software-related issue OA-13646
The issue will be permanently fixed in the future platform release.
As a workaround, pau transaction timeout could be temporarily increased according to the article.