I did my first track day a few weeks ago and didn't have any issues like this. I kept the TC/VSC completely off (orange). To my knowledge, this doesn't disable ABS. I don't think ABS can be disabled.
The only time I've seen other Subarus have issues like this on the track, it was either caused by overboosting and hitting fuel cut or by not having enough fuel in the tank and starving the pump because the fuel moves to the back of the tank under a long stretch of acceleration.
Since you are stage 1, I highly doubt it was boost fuel cut. How much fuel did you keep in the tank?