From time to time I hear about problems that MEINT menu is not visible in MII in ME 15 system, even though all necessary roles are assigned to the user. Such problem is mentioned in SAP Note 2082658. However, the software components update is not always required. It seems to me that the problem can be caused by deployment (I assume by deployment in a wrong order). Below are the steps that help to resolve such problem in some cases:
1. Redeploy ME.
2. Restart NW.
3. Redeploy MII.
4. Restart NW.
5. Redeploy MEINT.
6. Restart NW.
7. Re-run MEINT CTC.
8. Verify if the problem is resolved.
As you can see the idea is to assure the correct deployment order.
Hope you do not face such problem, but if you do these steps help.