2nd Alert time swaps with 1st Alert

Often after I set the 1st alert, and them set a 2nd, my iPhone reverses them so the 2nd becomes 1st & visa versa.

This is not human error it happens a lot and when it does, the only way out is to set both Alerts the same like 1 hour, & then set the 2nd from 1hr to 15 mins.

Any thoughts?