OK, I just did a Category Enforcement race and as far as I could tell it would only allow me to register for my ZwiftPower Cat or higher. I don’t think Zwift realizes that the problem is not not that the A riders are signing up for B races it’s that A riders are manipulating their data to stay a B…
Some B racers manipulate their weight in order to keep from upgrading to an A. I mean look at the watts they are generating but because it W AND w/kg they can play the game. On the flip side if a legit C rider does Zwift Crits and short races they will easily exceed the upgrade power and bam they are now a B. Your attempt at fair racing doesn’t address the problem. Try using what WTRL auto-cat does and look back at a riders most recent results and the type of race and then auto-assign categories.