Yeah the new update did not address any bugs it seems. It just added some content.
This is a crap idea but what if we ran 3 separate races and each race would be one stint. It would not be the same strategy since you would not be able to skip a pit stop to gain positions for example but it would be similar. You could still have the rule where you must run 10 laps on each tire compound, or change the rule temporarily to you must run an entire stint on each compound. I don't know. This would at least remove the pit stop tire bug from the equation.
Say a race was 75 laps. We race 25 laps and the top 5 get points for the first stint. Race 2 is 25 more laps and the grid is based on previous race results. Again the top 5 get points as per usual. Race 3 is 25 laps and that would be the final result.
I know this isn't exactly the same race format but most of the time the optimal strategy is to pit during the caution laps anyway. I know organizing and running a weekly series is a lot of work and it must be frustrating that GT6 is such a broken game. But it would suck for this series to die from waiting months for a patch that addresses the online gameplay issues.