How can you set the timer on a S7 to ring while the phone is in silent mode?

[AC Question]

I want to do some quiet uninterrupted work so I want to set a countdown timer on my S7 to ring after an hour, but I want to leave my phone in silent mode. I tried DnD mode and even with putting Clock on as an exception, the timer wouldn't ring. My old S5 didn't have this problem. Is there a way to fix this or should I just use the microwave timer in the kitchen instead?

 

[Rukbat]

Turn the ringtone volume down, but leave all other volume controls up.