Speakerphone mode in Phone app produces no audio.... speakers otherwise fine.

Hey guys. Curious little problem here. My 6 month old Nexus 6p doesn't want to work as a speakerphone using the stock app.... I've tried:

-Updating the app (to 8.0? from Playstore)

-Downgrading the app

-Downgrading from 7.1.1 to Pure Nexus 7.0 and 6.0 and Resurrection Remix 7.1 and stock 7.1.something

-Installing various versions of Gapps

Worth noting that the speakerphone works in Hangouts Dialer and Duo

and Speakers work as normal in every other app

HELP!

Also worth noting, maybe... when in a call Do Not Disturb icon pops up in the status bar but, upon pressing the speaker button, Do Not Disturb goes away