Phone won't stay on Vibrate

[ShaggyKids]

My phone is switching to sound after I've set it to vibrate. I can't have this happening at work. Any ideas how to fix?

 

[vasekvi]

My phone is switching to sound after I've set it to vibrate. I can't have this happening at work. Any ideas how to fix?

How long after? Can you get this problem to reliably repeat? Do you have any smart settings set up? Does it happen after putting the device in your pocket or does this happen with your phone just sitting there?

 

[Morty2264]

I can definitely understand how this could be an unfortunate problem to have while at work. As the user above me stated, does this happen while the phone is just idly sitting on a desk? Do you have any launchers installed, or any other recently-installed apps?

 

[NationalTrust]

Any battery saver settings on?