I've uninstalled, re-installed, and re-scanned the plugins, via Cakewalk's plugin manager (Sonar). Here's the problem: Real Guitar 4 works fine. Unfortunately, none of the patterns load up. Even if I copy them manually from RG3, nothing.
An email to
Music Lab has gone unanswered for several months on this.
FYI, the 32-bit part of RG 4 installs to the
Programs (x86)/MusicLab folder, while the 64-bit side installs to
Programs/MusicLab EDIT: Nevermind. I just saw the
fix on their website. Feeling silly (again).