Not sure why I indicated RT-click. Working from memory since I currently don’t have the problem but I believe it is a left-click issue since I select geometry by left-clicking. Apologies for the error!
Normal behavior is for the multiple geometry selection menu to pop up and stick when items are in close proximity and a user tries to select desired geometry. User then selects desired geometry in pop up and it then goes away.
Reported is a problem where the user tries to select close proximity geometry and the pop-up will flash momentarily then disappear. User cannot select the desired geometry as a result and must restart Rhino to restore normal behavior.
This problem has been around for a while (at least 1 year +) while running OSX 10.10. I just started running El Capitan on a new machine and will report if I encounter it again.
Hard to duplicate, but I believe it was with a very large file 500+ meg, and many hours (5+) working with it. It’s almost like some sort of buffer becomes full?