Thanks Mahesh for the response. I had the similar understanding however, recently in one SLT system, one user X has activated the config and jobs are running fine for Sandbox ECC system and now when i am trying for Dev ECC, initial loads (for DD*) are scheduled for longer time and not finishing.
Now, why I am saying about locking, because there is a Sandbox CRM job is stooped for now and when I am creating CRM Dev config, it is immediately completing the initial loads of DD* tables.
When I look at SM12, the MT* jobs, DMC_COBJ etc are showing locked with user X, moreover, system is creating MT* job for Dev ECC but loding is not happening.