There seem to be some problems with custom blocks. Miltant tried out custom blocks I recently created. He told me they were working fine locally but acted glitchy on the Obstacle Unit Hard server. Here is a video he made:
I myself tested the blocks in the editor, locally and on the Obstacle Max Map server, and they worked fine.
HAScrashed had a similar issue with a block he created:

I don't know what causes these problems. Maybe you know more?