The first symptom of this is that the logo is not rendered, even though test page renders correctly. When clicking on the logo, chromium will prompt for:
> outlook.live.com wants to Look for and connect to any device on your local network
Selecting "Block" renders the plugin unusable. Selecting "Allow" will allow the plugin to run, but a reload may be needed. After the fact, the setting can be changed via chrome://settings/content/siteDetails?site=https%3A%2F%2Foutlook.live.com%2F ("Local network access"; exact URL coudl be subject to change).
A more in-depth description of the background (although it's a slightly different use-case, and affecting Edge, here) is at https://learn.microsoft.com/en-us/answers/questions/5647994/3rd-party-app-unable-to-call-our-end-point-in-edge .
TL;DR: Chromium blocks loading, because the load is initiated from a public network (outlook.live.com), while the plugin is served from the local network.