I am also having this issue with my Sixes. I will do a full reset and then it works fine for that short period of time, but I get the problem all over again if I switch to any other input and then come back to bluetooth. For some reason, it seems like the speakers stop sending out the "find me" signal or something...
ALSO, I am having a weird issue on TOP of all this that maybe the hive-mind can help with....
If there is any quiet part in dialogue (youtube videos of people talking especially) or music with any quiet between notes, the next sound will be cut off. The first beat of every track gets cut off like the speaker is going to sleep when it perceives even the slightest silence. During dialogue (provided there's no background noises) when one person is done talking, the first word of the next person talking will be cut off.
Is this some power saving setting that can be disabled?