Contribution Summary report only shows first 50 entries

Hi!
I've noticed that the Contribution Summary report only shows the first 50 entries, without giving you the ability to move to the next set of records.
Bottom-page statistics also calculate those 50 displayed entries and not all rows.

Narrowing it down, I was able to make it work again by commenting 3 lines on the function buildRows. The offending lines:

CRM_Core_DAO::disableFullGroupByMode();
CRM_Core_DAO::reenableFullGroupByMode();
$this->addToDeveloperTab($sql);

Source code reference here

Only when all these 3 lines are commented/removed, the report displays all records with a proper pager.

Anyone can shed any light why is this happening as I can't seem to be able to find out the reason?

Spotted on CiviCRM 5.16.2