Dear Kel,
I am also facing this problem.
You are right as per your testing system not allows the creating of PR throguh ME51n and user sttus works fine.
But when you create PR through project systems in CJ20N by assigning material component to neiwork activity it not works.
I think sujit is also facing the same problem.
How to restice the PR creation with current user status setting through project system CJ20N
Regards,
Pradeep