I've noticed a strange issue when starting up Edge fresh (ie: no previous running instances). When loading a CSS heavy page, such as Microsoft.com, the CSS is missing for a few seconds, then it loads. We are testing in our enterprise environment and some users reported this, and I can confirm this happens in Stable and Dev channels, in our managed environment and on an external system non-managed.
Is this an issue with the Blink rendering engine or something else? I've attached a screenshot of what you see. This will show for just a second or so and then load the rest of the CSS.