have you looked at the IC7300 setup instructions? it’s not too different other than the Icom “connections” menu settings are different for baud rate (19600), and ciV address (88). Here’s the 7300 setup: https://groups.io/g/RigPi/files/Rig%20Configuration%20Information/ICOM/ICOM%20IC-7300%20Setup.pdf
I only use the single USB connection between the rigPI USB and my Icom IC7100. I attached a photo of my advanced settings screen on the rigpi configuration settings.
When I run Mumble I close all other apps (WSJT-x, or jS8call) and you make sure that the Rig is “connected” using the main RigPI web app. All of the mumble settings are the same for the rigPI with IC7100 as they are with IC7300 so that guide is a good one to use for that.
Some things to check:
Check “device” in mumble, make sure you are using the sound card from the IC7100
Is your phone “mumble client” connecting to the mumble server on the RigPI correctly?
There are more things to check but my flight is leaving. Chat you later.