There was a company selling "true wireless ear buds" and this was one of the issues they had. Finally a scathing video review was done about it and the software/firmware/product issues and the company folded as they were never able to fix the issues.
If your product has failed, just head to the refund as this issue was never resolved and my bet is the buggy product would come back under other names.
I've got this pair of wireless earphones called the ESONStyle S990. They are pretty good, but lately, I've had a challenging time getting them to pair to each other so that I can hear them both at the same time from a single source. I get in my Bluetooth list an S990L and S990R but I used to show just one of them and both would connect to each other and then my computer or phone, depending on what I used at that moment. The documentation states taking them out of their case and they will sync to each other. It did that once, but now they seem to be stuck in a solo mode. The documentation is limited and I'm still waiting on a response from their support site.
Does anyone have experience with something similar to this on this device or a device like it?