Current questions and answers regarding the map editor.

Hello everyone. I've already figured out what not to do when creating my own arena to avoid unnecessary hassle, but the question is still interesting:
how are blocked tiles calculated? I did it this way - and it worked on the first arena - I took 30.42 for MountPoint with a rotation of 0. I made a fixed ObstacleGroup with an empty model and a block of tiles - I calculated it by trial and error (I took coordinates 27, 29 as zero). The arena is 72x72.
I'm trying the 2nd arena - everything is the same, but now it seems like the 'zero' has shifted. I managed to make a tile block 30, 30 (and it was in the upper right corner of the arena) - but in theory, if you count from 'zero' (27, 29), the tile should be outside the accessible battlefield.
So, how are these Obstacles calculated?

Has no one encountered this problem?