[Cal578]

Mecanum drive is fun. It can be complicated, so it's good to see that you're working on it off-season.

A mecanum system is sensitive to torque and traction. If you're driving each wheel directly from a motor, with no gearbox, then you'll have wheel slippage and/or motors that are at or near stall. This can contribute to different speeds depending on direction. Also, where is your center of gravity? That will also impact traction, and will be different depending on the direction of acceleration. Frame rigidity has a similar effect.

The forward-to-reverse "death" may be caused by the direct drive. When you change direction suddenly, that's a huge current draw, temporarily worse than a short circuit. If the motor controller detects an overcurrent, it will throw an error and stop. You may be able to handle this in software and reset automatically. A better way is for the software to not allow the sudden reversal; it can ramp up to the desired voltage in the other direction. If you're using Jaguars and CAN, there is a command that will change the voltage over a short period of time. Best to do both the voltage ramp and add a mechanical reduction between the motor and wheel, to improve torque.

I hope this helps. Keep us appraised of your progress. Pictures are always nice. 8-)