Thank you for your post.
Preview will display all records in the found set, so if you are viewing all records, then all records will appear in Preview. Instead, find for the one record, and then go to Preview.
Make sure you are using FileMaker Pro 14.0.5, as previous versions of FileMaker Pro 14 could cause a crash with a sorted portal. If you are running under Mac OS X, then post the crash report up to and including the crashed thread.
Thank you for the reply.
Your diagnosis was correct and your solution worked perfectly.