How to cancel timer completed notice via voice with ATOM ECHO

I’ve recently setup an ATOM ECHO M5 and I’m playing around with various automations. One of the features I want is a handsfree kitchen timer.
I’ve found that I can start and query a timer by voice just fine. The problem I’m having is that if the timer expires, the automation makes a sound and the ATOM flashes green, but I can’t stop it by voice. I have to press a button on the device.

The whole point of having a voice activated timer is to NOT fiddle with a device while doing something else.

Am I missing something obvious?