I am new to RW and just installed Stacks 2 on OS X 10.7.5.
I cannot use Stacks 3 on this version of OS X.
When I opened RW and selected a stacks page, none of the stacks showed up. I just get a blank box where the stacks should be. This is before I installed any third party stacks. I installed a few 3rd party stacks, then checked in the Finder Window: Macintosh HD/Library/Applications Support/Rapidweaver/Stacks and saw the stacks plugin and the 3rd party stacks I just installed and went back to RW and still get a blank-empty drop-down when I click on the Stacks selection.
This is a fresh install on a new (recently bought used) computer that never had RW or Stacks 2 installed on it.