Don't know why Avid have changed it.
There are several threads on this, but no solution:
http://duc.avid.com/showthread.php?t=328163
A workaround I'm using is:
1. Deselect the
Link Timeline and Edit Selection blue icon.
2. Select a clip or part of a clip.
3. Use Keyboard shortcut -
alt+Shift+5 (Windows)
Option+Shift+5 (Mac)
To speed this up, I use
SteerMouse for Mac ($20).
This is an excellent program for assigning keyboard shortcuts to mouse clicks.
A demo is available at:
http://www.plentycom.jp/en/steermouse/