MXT 275 troubleshooting

I recently installed an

$165 MXT275 MicroMobile® GMRS Radio – 15 watts Two-Way Radio with Integrated Control Microphone – Overland Caravanning Tractors – Detachable External Magnetic Mount Antenna - 8 Repeater Channels

MXT275 GMRS radio. I am using a 3 db gain ghost antenna mounted on my hood with an NMO connector next to a ditch light. The cable from the mount runs through the firewall and under the dash. The unit is mounted on the passenger side of the console. I used a fuse tap to power the unit, and plugged the fuse tap into the P outlet. I noticed last night that when the radio is on and I turn my ditch lights on the radio reception gets cut off. Has anyone else experienced this or have any idea what the issue may be? The ditch lights and radio are not on the same power source. I wonder if this is some kind of electrical interference from the ditch lights or Switch-Pros?