Legacy Family Trees: Tree collapses/Overlaps/ Wrong connections (1.121.361)

I have an Issue in my existing Save with the Familiy-Tree from the Laurent-Family / Arnessa Thor (Premade from my Wedding Stories) .

Tested without Mods! (And never changed a thing through Mods or cheats)

Arnessa ist shown as her own Sister and/or Mother which doubles / tripples the Familytree (depends on from which perspective its shown)

shown from Arnessas Perspective:

shown from Hectors (Arnessas Son) and Jaces (Arnessas Grandson) Perspective:

In an new Save the Familytree (including the Connection to the Thor, Kappe and Monti Families) is correct.