Hi Sam,
Perhaps it was accidental. When I preview the form it tells me that it cannot find the source code. Also, if I go to Tools > Form Options > Programming, I see the project location for code: C:\Documents and Settings\sbcamb\My Documents\InfoPath Projects\Add Recommendations Test\Trial - Master Detail.vbproj. I'm guessing that qRules doesn't like this (can't coexist with code) - that's why you don't even get an error message popup.
Anyway, I figured out a way to fix this without having to recreate the form.
1. Go to Tools > Form Options > Programming and remove the code.
2. Save the form template
3. Reinject qRules.
4. Preview, try it, it works!
EDIT: Hilary, you're too quick for me.