Since I've updated to the latest dev build from an earlier release my tablist order messed up.
In the past it was in alphabetical order, but now I don't get it at all ..

What server version are you running? Are you behind a proxy?

latest PaperSpigot, 1.10
Nope, I don't use a proxy.

It happens since the "addPlayerPrefixToTablist" update, even I'm not using it

Okay, seems like it has to do something with different /scoreboard players values on my server. I think you don't touch this, right?