Strange behaviour with collapsing belt

Hi captains,

I got some strange behaviour with belts. I run them down a slope.
The area where it is is 100% flattened, see screenshot

Now when I remove that collapsing part it pops up somewhere else on the conveyor line, see second screenshot.
it is also perfecly flat at the second spot.

Removing the second collapsing spot also pushes it further down the conveyor line, see 3rd screenshot

ok now something goes completly nuts: on the left side you see my conveyors and the pipe burried by a landslide, on the right side you see the collapsing icon on a perfectly flat surface

Presumably that's the middle spot of the very long conveyor/belt. It does the same thing when placing the pause icon