Well, this is the first time I've actually went over the plugin with 4.4.
When they announced built-in formatting with 4.4 my initial thought was they were just flipping a bit in some of the standard templates from OFF to ON, in which case this plugin would still be valid for edge cases.
However, they've done the thing more completely and aside from the top of the messenger message where it lists all the members in the conversation, everywhere else is accounted for.
1) Disable this plugin.
2) ACP - Members - Profiles - Profile Settings Tab, scroll to the bottom of the page:
Flip that to Global and save and you have this plugin.
I'll be editing the Marketplace description now but this is pretty much over and done with unless anyone can find somewhere it's not applied with that setting set to global.