2015 Elantra, PAC Radio Pro, Pioneer, OEM Backup Trigger Not Working

Hi All, I installed a Pioneer AVH-501EX in my 2015 Hyundai Elantra with the PAC Audio Radio Pro RP4.2-HY11 smart harness. I can’t get the OEM camera reverse trigger to work. MS CAN wires from the vehicle harness are going into the RP4. Trigger wire is coming out of the RP4 and connected to the trigger wire on the Pioneer harness. All connections seem correct based on wiring diagrams from all three parties. I verified that all settings on the head unit are correct as well. Camera will appear if I manually select it and put the car in reverse. I had one instance last week where the head unit powered on, but the video screen was black.   I put the car in reverse, and the backup camera appears.   Put the car in drive, blank screen comes back up. Reset the system and hasn’t happened since. Back to video screen, but no reverse camera. Makes me think it’s a power/current issue, but no idea where I would attach a step-up or relay. Parking brake trigger wire never worked either, also part of the CAN. Got around that one by installing a bypass. Any ideas on what’s happening here? TIA!