[BUG] Phosphor icons don't render

[digitaldiina]

Bug overview

Description: None of the phosphor icons appear in content. Prevents users from understanding what to click in a how-to.
Steps to reproduce: Go to https://app-superoffice-docs-dev.azurewebsites.net/en/learn/getting-started/main-screen/navigator
Expected result: See icon
Actual result: placeholder square shown instead

Additional details

Environment: Edge
Logs/screenshots: