Per the discussion in this thread:
an old bug with the way maps are indexed in Game->*ComboSolid has been fixed in the next version of ZC. This function now works the same way as other combo editing functions.

Starting with the next release, old quest and scripts are affected in the following way:
- Old quest behavior is unchanged when played in ZC.
- Old quests that are saved in ZQ, but whose scripts are not recompiled, will continue to function using the old behavior.
- Scripts in a quest (old or new) will switch to the new behavior when recompiled. You must correct your scripts to use the corrected map index before recompiling your scripts.

If you are currently using a 2.50.3 RC and are using scripts with these commands, you quest is currently in a twilight zone bugged state. Updating your calls and recompiling once we release the next RC is strongly recommended.

We apologize for any disruption.