Running PHP 5.4.29 with K2 version 2.6.8 (recently upgraded) on a Joomla 2.5.22 install. K2 doesn't resize images upon upload. I checked category settings for image size options and they are all blank (default). When I go into K2 Media Cache and download all flavors of the image they are all the original size I uploaded. Any thoughts on how to troubleshoot this?

Hi. This has already been fixed for the next update. Until then you can apply the changes on your own github.com/joomlaworks/k2/commit/e5ea56e4d1923404a085ea463e4d1632e4c4659f . Actually it is the upload class that K2 is using. Let me know if that solves your issue.