Webmail Calendar - recurring series exception missing data

We use recurring events to book in clients.  When an available slot is filled, the client info is put in the box of the event, so it becomes an exception to the series.  Makes sense.  However, if you look at that exception again after saving the changes, the body portion of the event is completely blank.  This happens in webmail ONLY.  If I access the calendar via the desktop app, all the client information is visible.  Our staff all use webmail and this was working fine up until this week - I can't find what changed!