Addons uninstalling on their own (steam version)

This has happened a few times now where a few addons have uninstalled themselves, all marketplace bought, specifically this has happened a few times with the free Aerosoft airport, the CRJ and now with the new Asobo aircraft added to that list.

After the most recent time it happened I checked my install folder and these addons have disappeared without a trace. This is getting really annoying, especially considering they total 16GB and that takes a while with how slow the content manager is with downloading things.

My community folder has made no difference, I ran with only marketplace items for a while and got the same thing again after a few days.

Also sometimes my default aircraft would disappear on their own, mainly with the 208.