Plum TreeApp

Hello, fellow Simmers! *waves*

I hope it's ok to creat a new topic. :)
Does anyone else use the PlumTree app?
I noticed that linking to other trees doesn't work anymore for me, even though the tree ID and person ID are correct. I also re-linked them, but that doesn't work either.
Does anyone else have this problem and knows how to fix it?

As an example, here one of my trees.

Thank you very much for any help!