MES Customisation not taking place in Epicor 9, but works in Test

I’ve made customisations in the development MES and works when I’m the test Epicor system, but not in the live system.

I have the exact same customisations in place and the same Menu Items and are both pointing to the same customisation (the test MES pointing to the test customisations, and the live MES pointing to the live customisations).

The customisation is to add the Job Closing form to the MES so that some users can re-open jobs that have been closed early.

As mentioned above, I’ve created a copy of the customisation into the Test Epicor MES and the Live Epicor MES systems. I’ve added the customisations into the relevant Menu IDs (both named the same), the Test Epicor MES system works when started, but the Live Epicor MES system doesn’t bring up any customisation.

Also, it would be ideal if this can only be only accessed by certain MES users.

-Why is this the case?
-Is it possible to only make the customisation available for some MES users instead of all of them?