I was also using a Child Theme of Woothemes Canvas Theme. In my case, it was resolved using the following (I found this solution in this site – http://www.pootlepress.co.uk/2013/06/65-tips-tricks-and-css-tweaks-for-woothemes-canvas/):
Fix for BBPress and Canvas (5.2 and higher)
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Matty Cohen from WooThemes provided the fix for this one 🙂
Add a file called “bbpress.php” into your child theme. This file can be downloaded here: https://gist.github.com/mattyza/1b01583441b11c8d04d0
Add the following code in the designated area of your “functions.php” file: https://gist.github.com/mattyza/f210cadb7f70188d513d