SSO broken when using border proxy

[apereira-dcca]

• Your Rocket.Chat app version: 4.6.3.294
• Your Rocket.Chat server version: 3.0.12
• Device (or Simulator) you're running with: iPhone XR

I have set up RocketChat on an internal server, and I am planning to make it available to my users when off-site using Microsoft's Web App Proxy. Currently, this configuration is working for all web browsers I have tested (Firefox, Chrome, Safari on iOS, Firefox on Android). However, the iOS and Android apps will not complete authentication when outside my network.
In both iOS and Android apps, when connecting via the Web App Proxy (which is configured for pass through of all traffic, it's meant to be transparent), I am able to connect to my server, click the button for SAML authentication, and then I am redirected to my IDP (ADFS 4.0). I successfully authenticate, and I am redirected to RocketChat. Then, after a few seconds, the page that opened for SSO auth closes, and I'm back at the "Company Login" button.
Authentication works normally within the network, but my users are not permitted to connect their phones to the corporate network. Is there a way to fix or work-around this log-in bug?