Sometimes the thanks button on a post doesn't show. One of 2 things then happens. The first is that on the left hand side of the post there is a message about removing thanks. If you click on that, the last one who thanked a poster is deleted but the thanks button reappears. As soon as you thank the poster the left hand message shows back up and everything is hung again. In the second situation, the thanks button is simply gone. I have noticed this twice tonight and several times in the past.
I have tried right clicking, double clicking, etc. but can't figure out how to make the button operable.