More updates! We also found that it was Read&Write for Google Chrome causing our problems. Unfortunately, our board does not allow us to disable it. However, in working with them we discovered the following (from my discussion with our IT staff):
"We push the R&W extension in 2 different ways.. We use the Google Console to force install the extension via the user profile signed into Chrome. (This is the one I was able to turn off , and then the app started to work)
We also push that extension via GPO (Group Policy) for our Windows devices (device based) so that even users that do not sign into Chrome get the extension. (If I open Chrome without signing in R&W will still show up on a Windows device). It is not the same as the one applied through the Google console, and this does not appear to break the process.
The downfall is, we cannot use the GPO method to apply the extension to Chromebooks, forcing us to use the Google Console to do it.
I also compared all other settings in the console side by side by side for my test account and one that did not work.. and everything was identical, the only thing that fixed it was disabling the R&W extension that was set to be applied to users via the console."
Maybe that will help those of us who can't disable the extension?
Thanks again for all your help -- here's hoping you can get the WebRTC connection working for iOS again!