Sorting a page with external pagination always sorts and displays the first page

When applying display tag to paginate with external sorting, if a user moves to the 5th page and then sorts that page, the displaytag table shows the first page of the list instead of the 5th.

My table:
<display:table name="LISTA" pagesize="50" sort="external" partialList="true" size="<%=resultSize %>" id="my-id" requestURI="#my-id" class="display-tag-table">

Expected behaviour: 5th page displayed and sorted.
Actual behaviour: First page displayed and sorted.