Alarm sound although vibration only set

  • Fenix 5s plus

When alarm is set to vibration only, the first one is correct, 

but for the following ones (when sleep is selected and alarm is repeted  ) sound alarm is activated with vibration.

It's very annoying, because we choose "vibration only" to not disturb , and finally the alarm makes noise.

I think this happend when alarm is set to sound +  vibration first and then is modified to vibration only.

Does anyone experienced this ?