I may be wrong, but try another power supply for the Pi. It is possible that it is furnishing just enough current to keep the Pi alive, but additional load could be falling below operating threshold.

Thank you very much! A prod in the right direction is what I was looking for. I had things working with a pile of spagetti code and discrete variables, but maintaining it due to minor changes was looking to be a nightmare. For this section of the project, I hope my efforts help someone down the road...

Green to Python but an old fossil to computing, I looking for a call/create method for one created static child process per motor for a robotics project. Here is list of motors and parameters Motor #, device addr, bank, type, pin assignments. For the FiveWire the relative pin order is for IN1~4 For ...