Crumbling FOFs falling faster than normal

I have run into a problem involving Crumbling FOFs that causes them to fall faster than they should. I am unsure what could be the cause of this, but it doesn't seem to affect every one of them.

This is the FOF in question.
http://i.imgur.com/3VDYjzr.mp4

This is what it looks like in Zone Builder.


For a comparison, this is one of the other crumbling FOFs on the same map.
http://i.imgur.com/3dG8AX6.mp4

Any reason as to why this is happening?

It could be because the crumbling FOF is tagged to multiple sectors from one linedef, which would be a bug with SRB2. I know there's a similar problem with floating, bobbing FOFs at least, where tagging the linedef to multiple sectors makes it move faster than normal.