Re: ax-12 motors voltage?
Why are you using Reg Write at all? It requires you to first send data to the various servos (which may or may not immediately end any previous movement), and then later send a second packet to make the servos so anything at all (don't think there is any maximum time limit). If you need to control multiple servos simultaneously, use Sync Write. Much easier and faster than a bunch of Writes/RegWrites, but with the simultaneous execution of the RegWrite when the packet's checksum is verified.
The very well regulated 12V SMPS from Robotis is capable of sourcing 5A. During attempts to use a 0.4A 12V supply to power an arbotix and only a single servo, I could not reliably use PyPose as the servo would frequently fail to communicate. If you are having lots of problems, remove some of the servos from the daisy-chain and try again. If it starts working, you probably want to try a different power supply with a higher current limit.
Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
"You have failed me, Brain!"