I have put a brand-new MacBook Air A4 into operation. It is running the latest macOS Tahoe 26.2 and the current version of FotoMagico, V6.8.1.
When trying to create a new slideshow, none of the images from my Photos library are displayed. I have repaired the library, but I still have no access to the photos and videos it contains.
Found it. Crazy! You have to set the only one Photos library as the system library, then it works.
Too early to be happy. Now folders are shown, but without any loadable content.
Yesterday night and this Sunday I went through the usual ritual: reinstalling macOS Tahoe, restoring the Photos library from backup, re-declaring it as the system photo library. Predictably, none of that changed anything.
As a final experiment I installed PhotoMagico beta 6.8.b2. Without any other changes, the problem disappeared and everything works as expected again.