Hi there- sorry to hear you’re having problems with audio. This is an unusual problem; my first impression of the problem is that the audio system is set to Surround, but your listening environment is set to Stereo. That would explain the lack of sound at 180 degrees from the origin of the sound. Maybe can you check that? The UE4 audio system will use whatever the Windows/OSX audio channel count is set to.
Best-
Zak