The filter stopped returning results after I upgraded to the latest version of K2. So I checked the back-end and the module is returning this error:

Warning: htmlspecialchars() expects parameter 1 to be string, array given in /nfs/c04/h01/mnt/68436/domains/campspotr.com/html/libraries/joomla/form/fields/text.php on line 52

Eg: here is the front end of the filter... campspotr.com/index.php/search/k2-filter

Any thoughts? This error has me stumped. I'm on Joomla 2.5.8, if that helps. I've attached a screenshot.

surely somebody there has some insight to share. does the filter module even work in the latest version?