Users permission Problem into Thingworx 7.4

We have a problem with the users after the Upgrade 7.2 to 7.4 Thingworx.

Our user who is part of the administrators group has no permissions to edit any user ( Not even our users ).

We can create them, delete them, but not edit them.

The message that appears is the following

Error requesting edit, server error: Unable to Request Service RequestEdit on xxxxxxxx: null

Thnx

Giuseppe Fiore