The ical file is not working properly with 5.52 or even on the demo site http://demo.wp-events-plugin.com/events/molly-hatchet-2014-01-03/. The file that is created only has 4 lines.
This effects the placeholders or just going directly to /event.ics
This is the contents of the ical from the demo site.
BEGIN:VCALENDAR VERSION:2.0 PRODID:-//wp-events-plugin.com//5.5211//EN END:VCALENDAR
I have tested this with no other plugins enabled and am still getting this problem.