Rick Marx I think I isolated the cause. The Revit customization folder in my Roaming folder was not created during install (there was a mystery extension-less file in there preventing the folder from being created, maybe due to a failed install). I cleaned that section up and since then Enscape has been running fine.
So probably not the same underlying issue as other users were reporting here, just the same symptoms (greyed out Enscape bar, which I guess means Enscape failed to initialize properly?).
Can you please elaborate on "The Revit customization folder in my Roaming folder was not created during install" and provide details of fixing this issue? As far as i know, Roaming folders (for any application) are not created at the point of installation but at the point of opening application for the very first time.