I upgraded TMS VCL UI Pack from version 13.4.0.0 to 13.5.0.0 and I have an error "Class TAdvPage not found" on opening my project with TAdvOfficePager and TAdvToolBarPager.
I also noticed that when I create empty project with TAdvOfficePager I cannot add new page, so I think it's easy to reproduce.
I have found that is connected with last update of Delphi/RAD Studio 12.3. After reinstallation of TMS VCL UI Pack v 13.4.0.0 this problem also exists but on Delphi 12.2 this error did not exists.
So, I don't knot what to do, return to Delphi 12.2 or wait for update Delphi or TMS VCL UI...