[kamocat]

First off, 12 is a lot. I've only tested 9, but it's supposed to work up to 16.

I'll assume that the number of Jaguars is not an issue, that you've updated firmware on all of them, and that they all have power.

You probably have an issue in wiring your CAN bus.
The cables should be straight-pinned.
Make sure your termination resistor is not shorting.

What happens if you switch which Jaguar is the bridge? Do they all have the same issue?