2019 Greenpower Ev Star Bus

The incident occurred while driving my company's GreenPower EV Star Bus. I made a left turn from the street into a parking lot, when without any warning, the bus lost all power. I came to a stop and applied the parking brake. I couldn't restart the bus. I called the bus dealer. They said to check if the wheelchair lift was fully stowed. It was stowed. The parking brake light remained on. I went back and lowered the ramp and put it back up again. The parking brake light went off. I was then able to start the bus. I emailed GreenPower’s representative. He said to check if the hydraulic fluid in the lift was low or not, and to operate the lift each time before driving the bus. He said the ADA lift is designed to keep the vehicle from moving if the ramp is not in the full lock position, but I started and drove the bus for 10 miles before the power suddenly cut out, so this system didn't work. When I said there should be a safety system to prevent the wheelchair lift sensor from shutting the bus down while moving, he said the system was designed this way and he hasn't responded further. There was no accident so no insurance/police were involved. My concern is that if the bus is actually moving, any action of the wheelchair lift shouldn't cut off power to the bus, as this may cause an accident. I've had a few gas-powered buses with these lifts and we've never had this issue. Our gas buses have a "Park" selection for the transmission, and it must be in "Park" or else the wheelchair lift won't operate, and the wheelchair lift cannot shut off the gas motor while driving. This obvious safety feature is not found on the GreenPower EV Star electric bus, because it does not have a "Park" position on the shifter, but only Reverse-Neutral-Drive. I believe the lift was shaken/jolted while I was turning and going up into the parking lot, and the wheelchair lift sensor, showing the lift was deployed, shut the bus down. Or it was installed wrong. The bus is available for inspection.