Can you verify with the latest build? I havent had this problem. There have been thumbnail issues in earlier beta builds.
PS... am updating package as we speak to fix your legacy GAS_forumdisplay issue. Also found a hard coded phrase in the same line so I took that out.
I have also put the article and comment button images in.
To upgrade, replace all files and then run the Phrase and template install portion ONLY (or you can always pass... it really only fixes the display if using legacy forumdisplay)
Here it comes