Don’t know if this is right topic, but I had same kind of issue yesterday. External USB3 hard drive was connected straight to u-track. Formatted it with u-track and started to record rehersals strait from card’s rec-button. It has stopped recording around 55 min from start without any reason. X32-rack runs on latest firmware and this was the first recording with that firmware. U-track is connected to ethernet switch, but no software were used during the session.