Had the same issue with my Crossfade, Earlier left speaker was working but right speaker was having this issue and sometime i had to dab it to work properly but later left speaker has stopped working and right was working sometime and sometime not.
Tried reset it by holding + and - button together till 3 sec when until you hear a wave sound. then tried to connect through Bluetooth again but only right speaker was working.
Then i tried Jack plug-unplugged method with provided vmoda cord many times, this one also not helped.
Then tried plug-unplugged method with different 3.5 mm jack just 1 time and yeah! it worked. Strange! but yes it worked.