I just started having a problem using the one_third shortcodes, I have a few pages that were working up until today (4/4/13), now they seem to be being ignored. I have no problem with the pages using the one_half shortcodes, those are working as they always have been. I have updated Ultimate TinyMCE but disabling that didn't fix the issue. I also upgraded to Better WP Security, but am reluctant to try disabling that.
Any suggestions on how I can figure out what's causing this particular issue? It seems strange that only the one_third shortcodes would be ignored, or why a security plugin would make only one shortcode stop working.