Confirming what Boojumsnark said.
I had this same problem with a map for ZPS. I tried all sorts of wacky things ranging from parenting to physics tricks to get it to work, spending days just experimenting to see if anything would work. The bottom line is that a rope will not reset if it moves.
Your options unfortunately are limited to not having it break, removing it entirely, or replacing it with a model (probably not an option since it's last minute for the artpass deadline). Though depending on how you're using it, maybe you could set up a trigger_wind to blow it around wildly so it at least reacts to the explosion.
Kep