Curious. Drove my 2019 Sierra to the landfill to drop some trash. Drop off is a paved area. Leaving the site, got the Park Assist Blocked message. Noticed the light on the switch was off. Drove on and the light on the switch came on. Short time later, it was off and the message came back. Here's the kicker, I could press the switch and get the park assist off message. Hit the switch again, and the off message would go away, and the blocked message came back on. The truck has been parked since last Thursday and I had just returned from a 2800 mile round trip the Saturday prior. All sensors are clean.