I discovered what appears to be a bug that exists in versions of AutoMapper after v6.02 (confirmed with v6.1.0 and later).
If lines 22-23 in the RegistrationData.cs file are commented out (any version of AutoMapper), then the included code will run without issue.
If those lines are not commented out, with v4.2.0 (original version I had when this was working) through v6.0.2, it will run without issue.
Starting at version v6.1.0 and on, when Map() is called (line 29 in Program.cs), an exception is thrown...
System.FormatException: 'Input string was not in a correct format.'
This error isn't too terribly helpful (would be nice to know which field this relates to, I had to try each to narrow it down.)
Is this an issue in my code (some breaking change between those two that would explain this and I didn't account for?)