Hi,
Thanks for reporting this.
The menu that is flying out is actually the problem. It should not roll up the moment you move the mouse off of it. It should remain on screen and allow you to pick again. The intent is for two clicks to happen, one (RMB) and one (LMB) to pick an item from the folded out menu.
Please confirm this: Are you holding control + pressing down on the trackpad, and then sliding your finger to the menu item, and then lifting your finger when the mouse is on the item you want to select?
Try this*: pick the menu using control + tap/click. When it pops out, pick the item you want with another click.
*Testing your scenario I found the bug I mentioned at the top of my reply: sometimes the menu does not remain displayed. If this happens, pick something else in the data panel first, then right click on the thing you want.
Another workaround is to change your mac preferences to allow RMB actions in different ways. Sorry for the inconvenience.
Regards,
Phil Eichmiller
Software Engineer
Quality Assurance
Autodesk, Inc.