How to disable Fenix 8 Lap Tone?

I have a watch app in which the lap button is required to be pressed to cycle through phases of the activity. 

On all watches prior to F8, I controlled tones within the app, which could be disabled if the user desired. 

Some users running F8's have reported that there is still tone that's played when the lap button is pressed, irrespective of the tone enable/disable setting in my app. 

It seems the tones for the other buttons and functions are able to be disabled, but lap button press tone remains persistent. 

How can I go about disabling this within the app? Within the simulator running a fenix 8, all tone functions operate as desired.