Not sure, would that be set in QMC, I am still a bit new to administering QLIK, I assumed that adding the user to an assigned CAL, would give them access to all the published apps. Which I'm guessing is not the case.
I think it depends on the set up (I'm far from an expert in administration) but on the current set up we have we control who can see documents in Access Point by adding users or groups to the documents themselves.
Got to the QEMC, Documents > User Documents
Expand to find the application you've added and check the Authorization tab.
That may have a list of authorised users ... you could always try adding a person there to see if that helps. Have you got others users who can see the application in question? If you do, check their active directory groups. See if access might have been managed in that way instead.