I'm having this issue as well.
I'm starting to think it has to do with the pogo pins on the battery or the dish shape of the positive end of the battery compartment. Disconnection happens only during rapid movements it seems so power may be temporarily disconnecting.
It's been suggested that the pogo pins deliver power from the official rechargeable batteries and not the end terminals so the problem may be that they're getting shifted off the contact points under rapid or jerky movements, so the solution might be to pack the ends of the batteries, once installed, with something to prevent movement.
I went through hell with this problem. I contacted Meta support and at first we thought it was the right controller. They replaced it under warranty and shortly after replacement the problem started again on the new right controller. The common denominator was the Meta Charging Dock batteries. They replaced the batteries for me and shortly after that the left controller started randomly disconnecting. I then put the old left controller battery back in left controller and all was fine for a few weeks. Then the right controller started the disconnecting again. I think it was SpiraTech that suggested putting folded paper shims underneath the controller covers. Just enough thickness to make the cover go on tight. That seems to have done the trick. Since I installed the folded paper shims the controllers have not disconnected. I hope this helps.
That's my experience so far. After all my investigation, I have some shims at the top of the battery to keep it from shifting and a shim between the battery and door cover and it hasn't given me trouble yet other than the first connect after putting the measures in place. I popped the cover open, gave the battery a little nudge and buttoned it up, all is working fine now.
