WF not routing SSHR transactions beyond 1st level in supervisor hierachy

  I'm a bit puzzled with the behaviour of workflow for SSHR transaction such as leave, SIT's etc. We have setup AME so that it uses for up to 10 levels of the supervisor hierarchy. Now, it seems as this is working fine for most employees i.e. the transaction is routed to all levels up the chain following the supervisor hierarchy. However, for some employees we noticed that it stops at the first level i.e. the transaction goes to the immediate supervisor only and not beyond that.

This can be reproduced by attaching a supervisor - who is already linked to his/her supervisor etc > access Employee SSHR > Leave of Absence > Proceed to review page (where you will be able to see the chain of approval - based on the supervisor hierarchy.)