The Connect IQ fields cannot duplicate the second by second analysis of the XO server.
It’s not a reliability issue so much as precision based.
The best policy with the BT alert on the app is to keep going if you have anything left in the tank or go again like you did.
It’s possible you had two BTs (or Near BT) during that ride. Use the Previous button under the chart to confirm. The routine will adjust your signature accordingly to show only one instance.
Reference – Multiple BTs: Breaking Through the Xert Way! – Xert