1.30 Steam - Adding ships (mods) on steam platform bug

When I add mods directly on the steam platform, without the game running, the game does not download them. However the mods download fine, when I run the mod browser ingame (steam overlay) and add them there.

To get the game to download mods I have subscribed to offline, I first have to cancel the subscription of the mod, secondly restart the game and third resubscribe from the ingame (overlay) steam menu.