Advanced Search Using Custom Profile as Display View that Includes Groups Not Working after Upgrading to 5.9.0
Pretty sure the "1 row" problem only shows if you search using one custom Profile then switch to using a second custom Profile

Ie

Reset Form
then use Default, (all rows show)
then switch to profile with Groups field (all rows show)
then switch to profile with Tags field - only 1 row shows.

Reset Form
then use Default, (all rows show)
then switch to profile with Tags field (all rows show)
then switch to profile with Groups field - only 1 row shows.

So the problem seems to relate to switching between one custom search Profile and a second one.

NOTE: above came to light when trying to demo to Eileen that i could replicate https://lab.civicrm.org/dev/core/issues/679

UPDATE: Fix at https://github.com/civicrm/civicrm-core/pull/13533