[Mangos] Zero 0.20 - 1.12.1 Server - Not able to "Zone In" some instances

I'm running a private server just for me to play on and I'm using this REPACK. Everything works great except that I am unable to get into or "zone into" some instances (just run towards the instance portal and keep running into an invisible wall instead of entering the instance) like MC, Naxx, BWL, Ony, AQ20/40, ZG, however, some other instances do work, like Strat, Scholo, BRD. I'm not sure what the issue is here, and I am very new to all of this, just hoping someone can point me in the right direction as to why this is occuring.

Thanks