Within Ax20012 the UserOnline form no longer show the SPID, evne when you are connected to the same AOS as the user.

Instead we need to configure a REGISTRY to be able to get this information, direct in SQL-Server, the document below shows how to see the AX UsersID when looking at Blocking locking in SQL.

 

See full document on how , including the Scipts

How to Show Blocking users for Dynamics AX 2012