Vault doesn't seem to link properly with Herochat anymore, instead opting to use "PermissionsEx_Chat" which, when disabled, still doesn't link to Herochat. I'm not sure if this is a problem with Herochat or Vault, but I do know that it's somewhat problematic since I need players to have to spend money to be able to speak in the Global chat channel. I'm crossposting this to Herochat support in case it was a problem with them, but the reason I suspect it has to do with Vault is because Vault doesn't seem to link with DragonTravel either anymore, so I feel like maybe there's something else wrong with Vault.

Amazingly, I have no clue what the actual problem is from what you just described. Some things I can help with are:
A) Herochat doesn't do economy charges for talking anymore.
B) PEX_Chat is the implementation backend for hooking PEX to provide prefixes, it's not the PEX ChatManager plugin.

Now if you could please detail a: This was happening before update, this is now happening after update. I might be able to assist you a bit more.

I actually believe you just solved my problem with answer A. I didn't realize chatCost had been deprecated. That's a shame. Was there any reason for that, and when did that happen anyway? Because it worked up until just a couple weeks ago when I last checked it.

It was removed cause of spamminess. and the person who originally put it in isn't around to continue working on it.