So it seems like there is a problem with my server -_-
Me and my staff members where working on the server till one off em logged off and logged back in, it Appeared our skins changed to Alex and Steves for her/him now i just started up the server to work on it yet again with one off my staff members and it seems like both ours skins are changed to Alex even tough the server is up and online-mode is set to true, Could it be that UltimateCore is causing havoc about that?
Does this problem persist even when you take out Sponge (if vanilla, run regular Minecraft jar instead of SV jar)? Because this is one of the most common Minecraft server issues I know of.
well whitout SpongeForge my plugins and mods are down 
idk what happened but everything was fine till like 3 days ago i didn’t bother about it till now
I am fully aware of that fact. I am asking you to check if the problem persists without Sponge, not whether you can just remove Sponge from your server permanently. Please do the check I am asking, nothing is preventing you from putting SpongeForge right back.
i’l check in a bit since i am doing something on the server since we might be going up today
Edit:
after removing sponge from the mods folder my server gets in a crash loop o_O
None off these are added in a log nor could be found in any o_O
If you’re using UltimateCore, take a look into the tablist module and change the
compatibility-mode: true
will take a look at it