I'm having this problem, too. It's the firmware update. Our setup was working with 8 trackers and no power button issues until I updated the firmware just now. Our pipeline depends on these dang trackers and they're already super finicky to begin with. But, thanks to this update, getting all the trackers to pair is practically impossible. I've spent the last hour and a half screwing with them with no end in sight. Half of them won't turn on unless I trick them in to it by plugging them directly in to the USB cable. Plus I'm having all kinds of problems getting them all to pair again. I can usually get 7 to pair but then the 8th one refuses. So I have to unplug all the dongles and start again from scratch. It's like playing Whack-A-Mole and it's driving me nuts!
I tried rolling back to the previous verion of the tracker firmware but now the Manage Trackers utility in Steam VR no longer works :(