I've just Googled your query, and it says that to keep them in the case and just open the case to start the pairing process once paired then just pop them in and should work
I was having the exact same issue only the left ear bud had very muted sound coming through. At first i blamed my hearing, but i could clearly hear playback when holding the right ear bud to my left ear. I've rebooted several times and changed the eartip to the larger one. Now for whatever reason i only get clear audio from the left bud if i tilt my head sideways 90°