Maybe you have another party mod installed and you did not checked box prefix "Poll"
it seems that $vbphrase[poll_thread_prefix] word (Poll:) is missing.
in a search i made i see that mod "VSa - Thread Listing Make-Up" has this ability.
Check it, if you use it. Weird though that shows default icon.
Those are actually the only plugins I'm using. I've quickly checking through the settings, and not a single one of them seems to be responsible. I'll quickly try disabling them and seeing what happens.
Edit: Found the culprit; it seems to the category separator. I'll try and figure out away around this. Thanks!