No ERG on workout

I’ve twice now had ERG stick and not adjust on a training plan workout.
This morning I was 55 minutes into a 1h25 workout and it happened, so had to abandon and thus the workout is marked incomplete and will have to be done again.

Is there a reason for this as it’s happened twice now in two days?

Atv4k, Wahoo Kickr 1st gen, Garmin Vector 3s, Wahoo TICKR