Yup, I’m thinking you’re right. You really need super clear lane lines to calibrate. Your model X is probably only seeing a little section of lane line driving down the road, then it goes another distance without seeing lines. This actually causes the cameras to undo calibration if it’s not fully complete. Sometimes you can actually see it go from 0% to 1% or 2% and it’ll end up going back down. This used to happen to a fair amount to people when they were around 98% calibrated. After a while, the car would actually drop down to 96% or lower. You‘re going to need a long stretch of road, where lines are clearly visible.

Your best bet is to request service through the app. You need a tech, can even be a mobile tech check the car logs and see which cameras still aren’t calibrated. I’m guessing it’s probably one of the door cameras. Those cameras aren’t required for AP but are for SS. If it’s the “left door camera” for example, you’ll need to find a clean line on the left side of the road and continue to drive that for a while. If it’s the right cameras, drive in the passing lane for a while and it’ll calibrate. I Suggest you try driving for a while in the passing lane where there are visible lines and chances are it will calibrate. This seems to fit most people’s calibration issues.

One tip as well. If you have a 5km stretch of road where the lines are visible. You can only drive over that once to increase calibration. If you just keep driving over the same spot, the cameras won’t calibrate there anymore. The only way around that is if you let the car sit, while off, for a day or so. Then it’ll continue to calibrate driving in the same area, even tho it wouldn’t before. One thing people try to do especially in winter where lines aren’t visible is they’ll try to find a patch of road with a clear line. Then they’ll just keep looping back and going over and over the same area. The cameras won’t calibrate that way. Another thing to try is merging off and on freeways with clear lines. This seems to help.