Enclosure is not recognized / Gehege wird nicht erkannt

[sxsi]

Hello,

I just can't figure out what the problem is with my hippo enclosure. It has an underwater tunnel so the animals can swim under the paths to the second part of the enclosure.
There I used the invisible enclosure boundary.
Likewise at the points where the enclosure is limited by the high terrain.
There is also a path underground for guests to view the animals through glass panes. One side is marked as "not enclosure boundary", the other side is integrated into the enclosure boundary with the invisible barrier.

I already deleted the whole barriere and built it again, I've also paused the game and let it run for a few more minutes....

Help...???

Here are some hopefully helpful screenshots of my not reconized enclosure.

https://imgur.com/a/wvcrSyh