PEX Breaks After Adding a Group

I have an issue on my server where when I first install pex, it appears green on pl. However, after adding a group, owner for example, and adding a user to that group, the user is still shown as a default. After reloading or restarting the server, pex no longer appears in /pl. I've never ran into this before and have absolutely no idea what's happening. Here's a list of my plugins:

- Factions

- WorldEdit

- HolographicDisplays

- Essentials

- EssentialsSpawn

- EssentialsChat

- MassiveCore

- Multiverse-Core

- Worldguard

- PEX (when it's first downloaded)

Any help is appreciated!

Quote from Twenty

Remembee you have to set a prefix for that user, or else they will appear as the default prefix. I understand PEX breaking when /rl is used, but I have never heard about it doing so when the server is restarted.

Does this mean that group prefixes do not work?

EDIT: Just tried to move myself to the group and set my prefix and there is prefix and in /list I am still in the default group. When I restarted the server, PEX was gone from /pl. The jar file and folder are still in the files folder, but PEX just simply isn't on the server

EDIT 2: Problem solved, just missing Vault for EssentialsChat to work and updated PEX to the newest version.