Time stamp while playing

[MT218]

Hello,

Everytime I update my phone, the time indicator starts disappearing after playing for a few seconds and I have to tap the screen to bring it back on, then it disappears again. I am a fitness instructor and we rely on time lapsed and remaining time for our drills and need the time stamp to display all the time. Why does this seem to be caused by iPhone updates and how can it be remedied?