Each time skins are updated, or when a model in the game is updated, the game needs a new version of the "skins.res" file. Until you are connected to an online arena, the game cannot get a new version of this file. Until this file is updated, no skins will be available online.
Once you connect to an online arena, the game will install this file for you, if yours is out of date. Once it is installed, skins will be shown again in the hangar.
