The display isn't changing from mid pto speed to rear pto when rear only is selected. It also shuts off when backing. Is there an adjustment or maybe something that might be loose that I am over looking?
If it's shutting off while backing up then the machine thinks the mid-PTO is running. The RIO function only works with the mid-PTO and you should be able to test it by using the RIO switch when backing up. If the machine backs up without dying then the Mid-PTO is still selected.
The linkage on your PTO selector may be "off" and need adjustment.