Heart Rate Alerts Not Working With Intervals

Hello,

I'm trying to set up a trail run or run interval workout with heart rate alerts (I don't want my HR going above a certain BPM). Let's say I set my intervals for 10min run and 5min rest. Whenever I start my run workout, my Instinct doesn't alert me whenever my heart rate goes above my specified threshold. It seems like alerts don't work when using interval workouts. Is there a config I'm missing? Anyone else have this problem?

I have my alerts set under  Trail Run Settings > Alerts

I have my intervals set under Training  > Intervals 

Thanks.