On both my MacBook Air and my desktop Mac, when I try to grab a GeoLocation region where it is showing the Google Map image, I cannot resize the region with the drag handles. I grab a handle, and it moves about a milimeter, and then jumps about 3" away from the cursor. Happens on all 4 corners, and on both platforms.
This is on El Cap 10.11.3 (15D21). This MacBook is a mid 2012, 13". Desktop specs, but I think 2011 model 21.5" iMac. Same OS.
I didn’t see this reported here yet, but may have missed it.