Thanks for your answer Sankhadeep.
This issue is persisting for almost a month now and the servers were restarted every sunday, so I believe that eliminates the first two possibilities. Moving on the 3rd suggestion,
I tried giving the page access rights via "Global access rights" and I was able to view the sub page. But I tried giving the access right via OBS units and I was not able to view the sub page, even though I am under the corresponding OBS. One thing to be noted is that the group (to which view-all and edit-all access rights are assigned) has access rights via OBS units and not global. The OBS of the groups/resources/sub page are in alignment though.