Dulcisvolintarious

So I created a forge server for 1.12.2, most of the mods won't load and annoyingly? Inventory won't open, tried everything to open it. Idk what I'm doing wrong here. Single player works like a dream. I installed the server perfectly as per instructions. I tried Uninstalling all mods and tried adding them one at a time? Same thing; no inventory load no matter what mods where on there, even without mods. Tested for lag and to see if there was a conflict ie another server install messing with it? Nothing. Has anyone encountered this on 1.12.2? BTW yes I remapped the key, it also didn't work.