Missing alarm set symbol on iPhone 7

When I set an alarm, I’m not seeing the alarm symbol in the top right hand corner of my screen (next to the battery level icon).

• My iOS is updated.
• I've tried to delete and create new alarms, but it doesn't work.
• If I restart my device, it will show the symbol back again, but only for a day. The next day the problem is back again... So restarting its just a temporary solution.
• I've tried to reset all settings, but again, it works just temporarily. After a day, the symbol is missing again.

How do I get this symbol to show when I set an alarm?