Beats pro headphones left headphone won’t hold charge

So I’ve scoured the questions and this is somewhat different-

my left earbud of my beats pros WONT hold a charge.

ill charge overnight in the case, I’ll check to see the left and right are both charging by checking the percentage on my phone. The next day I unplug the case and the headphones and leave it next to my exercise bike. When I get home to workout the left earbud is at 0%!!! How can this be!? They just charged at night. They weren’t even touched throughout the day. What is going on? I’ve only had these for about 6 months and super disappointed. I bought these becusse I was having an issue with my old beats not holding a charge and always being dead when I go to use them (but they were 6 years old!)