Not sure if you got this problem fixed yet or not? But my Plaid developed the same issue about three weeks after delivery. And in my case it turned out to be the radar sensor that went bad. But.. my SC team had trouble simply replacing the radar with a new part. And they ended up spending days talking with Fremont engineers and looking at data dumps before somebody realized what the problem was with replacing the sensor. Apparently when the new exact part replacement is installed, there is still a "Factory Mode" routine that needs to be run before the radar calibration is done, to tell the car what brand of radar sensor is installed. Otherwise when the calibration for the new sensor is done, the car defaults to the wrong setting and thinks it trying to talk to another brand of radar sensor?
This is how my SC described the fix to me after a couple of days working on this problem. So just thought I throw the info out here in case it might help someone else. My visualizations, cruise control, and FSD do indeed work perfectly after this fix.. FWIW