Elias,
Not sure if you resolved this problem, but I had to change additional values in the DefaultScalability.ini in your config folder
The default scalable settings are stored for the Low, Medium, High, and Ultra Settings. There are groups of variables for each of the four settings in the file. The @0 settings are for Low, the @1 settings are for Medium, and so on.
r.AmbientOcclusionLevels
is set to 0. This defines how many mip levels your AO is using. Set it higher than 0 on the quality settings you are using on your project to get AO back in your project. Worked on my end.