Hello,
I have the same problem only I'm using the Sonos Arc Center Speaker (as long as eARC port is being utilied your bluetooth function will not stay activated). I have spoke to LG Engineers and they say only solution to this problem is to unplug anything in your eARC port when utilizing the TV Bluetooth function. This solution that has been offered by LG will eventually cause wear & tear on your eARC port constantly pulling HDMI plug in and out, LG has acknowledged this but says thats the only solution, Nice LG!!!! Worst TV Brand I have ever had, WebOS is terrible enough and now you have to suffer with these bluetooth problems, wish I could be more positive about your issue.
Regards