Elder influence not disappearing

I had elder influence on Core, killed almost everything (4 monsters left, the 3 minibosses and Malachai itself are dead), the influence is still on the map.

Hello there =]
Such thing can happen.
If the map you completed would cause the elder's influence to be cut in multiple pieces, and if that would cause elder and/or his guardians to be separated, then the map stays under the elder's influence.