I'm unable to pin or unpin terrain tiles, the only tile outlines that appear are the blue/orange ones that are already pinned with the HDRP demo scene.
Selecting pin or unpin does not display an outline and clicking an appropriate spot after selecting pin or unpin performs the default unity object selection.
I can place and see locks.
Gizmos are on, the gameobject and MapMagic component are enabled.
I'm using MapMagic2 Version: 2.1.6
Tested in fresh projects 2019.4.0f1, 2019.4.11f1, 2019.4.28f1
HDRP version was default for each install and then upgraded to the newest available package for that version.
Testing in a 2020.3.13f1 with default HDRP does pin/unpin as expected.