DaveORD- when you opt out and back in after the SS disappears from the app, you will be updated to 100 and lose score from there as you drive. At one time beta FSD invite happened after registering 100 miles. Some said it takes 7 days but I got it the day after driving 115 miles after opting back in and maintaining a 100 score. This was on my Model S and very early. Lately, Tesla has been slow rolling out updates to existing testers as so many bugs have been surfacing. We even get notice now of "aborting due to system error" This is showing up on v10.6.1
There is a second trick to keeping the score high: Say you have 50 miles and out for another drive and after 15 miles you get a high impact alert like collision avoidance. Instead of continuing to drive, pull over immediately and put your car in park. Now reboot the car with both scroll wheels. While it is rebooting get out of the car and close the door. Wait for the car to completely reboot and then get back in. The ding you just got will never be sent back to Tesla. You will lose the 15 miles and start over at 50 miles with your high score.
Another thing to know is that your score is a 30 day moving average of daily averages of daily trips. Basically, it means that on the 31st day your average losesc day one of your score.