[Tissot] [Build 0.6-o-2019061813744-dev-tissot] No audio while using the phone app (incoming + outgoing)

Behaviour showed up after I installed /e/ some days ago and is reproducable with the latest updates.

Neither the caller/called person is hearing me nor I am hearing them.

Workaround is to root the device and edit /system/build.prop in the following line:

#Additional_Build_Properties persist.vendor.audio.fluence.voicecall=true

Switch this line to false and it will work again.

This is only a workaround, the device should be able to do phone calls without it.