Did you try using the Ark Mod Tools located in ArkDev/ModTools to upload your mod? I had a problem uploading through the DevKit so I just used that standalone mod tool after I cooked it within the DevKit, pointed to all the right files (ModDir,Map, put a title name etc). The Description I would advise to copy and save it somewhere as the standalone tool doesn’t work that well with it.
Had a problem with the DevKit steam upload tool updating my deathfind mod so I went to the standalone tool and updated it. (was giving me some stupid limit exceeded error when I was try to update it).
Give that a try and see if that works out for you instead.