This time I reopened the 2016 Room and there was no problem with the preset popup list staying put like normal.
Yes, it displays v 2.1. (I don't believe v 2.0.6 would load into Logic X because 2.0.6 was 32-bit and Logic X takes only 64-bit plugins.) Logic X version is 10.0.3.
Oddly though, the first time (the one that gave me trouble with the menu) there appeared a popup message saying "iLok could not be shared across systems. Remove and reattach."
I don't share or move an iLok, so it didn't make sense and was not something I'd seen before. The iLok stays on one iMac computer. I have two user accounts on that computer, but only one user uses the iLok.
This time (when the menus worked normally) there was no iLok message. However, when I logged out of the Logic user account and into the main OS X user login screen, the iLok sharing message was back. I've never seen that before.
Does this give you any clues? Feel free to take this thread offline if it is an isolated incident.
