Unfortunately a recent update of Woothemes Canvas caused a problem with BBPress. Namely BBPress no longer displays properly and is broken. However there is a very simple fix and below I detail how to get both Canvas and BBPress working nicely together.
Download these 2 files
Upload both files into your Canvas theme folder. You can either do this via FTP or via your file manager in the hosting account control panel. This is the file path wp-content/themes/canvas. Just put both files in the Canvas folder.
Sit back and admire your work!