Full size photo no longer displayed

Two days ago I upgraded to 6.4.07 and today I noticed that when I click on a thumbnail that the full size picture is no longer displayed.
Instead of displaying the full size picture, it jumps back to the overview of all albums.
This happens no matter if I click on a thumbnail from the most recent, top ten or comment widget and also when I try to open a thumbnail from an album.
In table VI.A and VI.B the links for the topten widget, thumbnail widget, thumbnail, Sphoto and Mphoto are still defined as “the full size photo in a slideshow” as before.

You can check it out on https://photona.org.

Can this be related with the upgrade or am I facing another problem?

Kind regards,
Dirk

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