I'm not sure.
The problem with loading happens if I load bricks outside of the mission area, I can reproduce this bug at will... although, it looks like it occurs for other people while bricks are actually inside the mission area. Weird. It also occurs when bricks overlap, as I've found through experimentation. While I'm not sure what causes it, I'm pretty sure that it should be investigated.
I'll try reproducing the bug. If I load while I'm near the bricks, the overlapping doesn't occur, but if I fly over to an area that I loaded bricks far away from, the bug can occur. It might be something to do with server-client syncing. I just can't imagine what.