See screenshots - first raw, second with arrows. Used pak64 from release 110.0.1.
I managed to reproduce this with 110.0.1 executable as well.
It appears that this is triggered by some non-apparent condition, I could not reproduce this with 100% certainty (but it's very common). Adding another dock on the clipped side fixes this, but the new dock might be clipped again :-/
http://simutrans-germany.com/files/upload/Clipboard02.jpg
http://simutrans-germany.com/files/upload/Clipboard03.jpg
Does this disappear after rotating 4 times?
What after save & reload?
Both fix the condition.
Should be fixed now in 4381.
Confirmed :) Thanks!