Latest Update:
It seems to be an issue somewhere with the new functions created on lines 71-81 of imc/class-frontend.php. I’ve tried to replace the instances using those functions with the old code, but unfortunately it causes an error on the page.
I can also confirm that it works with both filtering and searching posts. Thank you!
I received the same message as well, but I also get it when trying to filter posts. If I downgrade to the last version, then everything works fine, so I’d have to agree with edwardnh that this is probably a nonce issue.
Here’s the change from WordPress trac that fixes it.
http://core.trac.ww.wp.xz.cn/changeset/18047
It looks like we’ll have to wait till 3.1.4 for it to be an official fix, but, if you want to fix it now, you can just make the changes yourself to the file and everything should be working. It worked for me.
