One particular user has a mix of calendars she has subscribed to using the %20 and 32 URLs. But one of the %20 calendars does not refresh (overlaying a red exclamation point badge on the "subscribed" icon in the Calendars list). All other %20 and 32 URLs refresh properly.
I've tried deleting the com.apple.ical.plist file, deleted and re-added the calendar--all to no avail. Other users can subscribe to and refresh this calendar without a problem.