You might need to update your PRL profile. In Settings go first to About Device*=> Status, and scroll down to PRL Version., which should be a five digit number; make a note of that number.
Now back out of the Settings Menu until you can see the System Update option, normally to be found just above About Device. Tap System Update, then scroll down Update PRL and tap it. While in progress, you should see "UPDATE PRL: Checking for PRL Update. Please wait", and then "The PRL has been updated. Press OK to continue." Tap "OK to complete the process. Be aware that the verbiage is the same whether or not the PRL was actually updated, which is why you want to first write down the existing number before you start. That's just so you can determine whether or not anything actually changed or not.
As you did before, now navigate to About Device=>Status to check if the number is now different from the one you noted down earlier. If it is, there's a good chance that this will have taken care of your mobile data problem. It's worked for me a few times.
*The location of About Device and System Update can be counterintuitive. If you use the tabbed menu view, they are under the General tab, rather than under Device as you'd expect. This applies to stock 5.0 rooted or otherwise.