I recently updated a working installation of DNN 5.1 and DUD 2.5 to DNN 5.2.2 and DUD 3.0. After the upgrade, no users would appear in the directory. I traced the problem to changes in the Item / List Template and User Detail Template that need to be made to work in the new configuration.
In particular, it seems that some of the tokens are case-sensitive so tokens such as [FirstName] cause an error and must be changed to [firstname] for anything to be displayed. In addition, some tokens such as [MidddleName] and [Unit] are no longer supported and should be removed altogether.
I'm not sure if the HTML will come across, but here goes... So for example, I had to change:
[FirstName] [MiddleName] [LastName] [Suffix]
[Street] [Unit]
[City] [Region] [PostalCode]
[Email]
[Telephone]
[UserRoles]
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to:
[firstname] [lastname]
[Street]
[City] [Region] [PostalCode]
[email]
[Telephone]
[UserRoles]
View Details