Level renders black/grey on Android?

Not sure if it’s related to this “bug” but I had also experienced some weird graphic glitches. My level would look fine on pc/mobile preview but on the device itself it would be very dark and some areas wouldn’t get any light at all.
Then I changed my directional light from stationary to static and now it is properly lit but I lost all my specular details, which is a shame. Is there anyway to fix this?