You can’t actually complete any laps, though.
Is this why I had to keep re-doing the last lap?
Hmmm I don’t think so, but I’m not 100% sure for your case.
This is my understanding of this bug. Ideally when you reset / go out of bounds it takes you to the last checkpoint. However, when you start the race you haven’t gotten any checkpoint yet so it can’t respawn you anywhere.
Which is why when you do this bug on track 2 after completing track 1 properly, it will take you to track 1 is because the last checkpoint the game remembers you having is back on track 1.