Anet A6 weird printer starts printing off of print area halfway though print

[Roberts_Clif]

I see you have determined that the SD card is the main cause of your problems.
Rarely ever printed from the USB Computer interface could not verify that it was only a SD Card issue.
But thinking about it believe that was the case for myself.

My problem was most times I would plug the 3D Printer to my Computer and it would reboot.
In Short the 3D Printer would short out my computer. Have always printed from a SD Card.
In fact still print from the SD Card on the 3D Printer, using the Pi's mainly to Stream video and preform minor tasks

Adjusting Bed and hot end temperatures
Preheat hot-end and Heat-Bed
Emergency Stop

Purchased Many Raspberry Pi's for different uses.