Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1673898

Description of problem:
When using any filter when generating the Registered Hosts report, the following red pop-up message is shown together with attached traceback:

"Cannot eagerly load the polymorphic association :owner".

This may or may not have been caused by fixing bug 1655628. This is a regression
because filtering worked in this report in some previous snap.

Version-Release number of selected component (if applicable):
Reproduced on Sat 6.5 snap 14.

How reproducible:
Deterministic

Steps to Reproduce:
1. Monitor -> Report Templates -> generate Registered Hosts report -> enter some filter -> Submit

Actual results:
Error message, traceback, nothing generated

Expected results:
Report generated without errors