We are having the same issue with Event Tickets Plus. The attendee information fields do not display on the front end after plugin update and therefore we cannot obtain custom attendee information. I have updated all plugins, checked all other plugins for conflict, and removed the template that was used temporarily. The theme is custom, but no luck finding any conflicts so far.
The RSVP custom attendee fields do show up.
Here is an example of it not showing: http://www.glenarborart.org/events/january-after-school-art-grades-k-4/2018-01-09/
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PLEASE LEAVE FOR SUPPORT
Reporting the same issue as: https://theeventscalendar.com/support/forums/topic/attendee-information-display/