Mapped items do not paginate correctly

[dheles]

Describe the bug
When a collection contains more than one page of mapped items (default: 10/page), using the pagination controls does not load new results. The same 10 items are returned with every page. (Observed in versions 7.5, 7.6, & 7.6.1 - current snapshot)

Test collection demonstrating this issue (must be logged-in as an administrator to observe):
https://demo.dspace.org/collections/d2cce7f8-f418-409b-aec4-a3ff7e4f04f8/edit/mapper?spc.page=1

To Reproduce
Steps to reproduce the behavior:

1. Map more than 10 items to a collection
2. Browse mapped items
3. Paginate between mapped items

Expected behavior
Paginating should load new mapped items

[tdonohue]

Can verify on demo site (via links above). Moving this to the 7.6.x board in search of a volunteer.