I cannot yet be sure this is a Hydrogen issues and continue to investigate, but the timing is certainly coincidental.
Since around the time I installed the most recent version (a few days ago) I have found my pages trying to load an Oxygen .css file of this form:
The encoded symbols render the file unavailable and I see 404s. This, of course, completely messes up the layout of my pages.
Regenerating CSS file in Oxygen does not…