[DonRotolo]

I assume during competition, and essentially not reproducible on the bench.

I speculate that it could be a physical layer issue: The electrical connections on the Bus are opening. Focus on the RS232 connection to the first CAN Jaguar in particular, see if you can ensure it is as robust as possible.

My reasoning behind this is that you appear to be seeing a complete loss of the CAN Bus, and the only place that can happen is before the first Jaguar. A fault after that point (assuming it is not the Jaguar itself, in some weird failure mode) would return different errors, and the first Jag would/should continue to function. As a serial connection, a complete loss must be at the start of the series.

I'm not a programmer and have no experience with CAN in FRC, but I've been using CAN Bus since 1997 at work. There, the Bus is always wired in parallel.