Hi,
'forums.sufficientvelocity.com' is not working correctly, when there are a lot of threadmarks, the site shortens it, and the plugin does expand the list to download more, but it only does it one time, if the site shortens it multiple times due to the number of threadmarks, it will only work the first time.
I didn't test it, but it maybe happening with 'forum.spacebattles.com' too, since they use the same system to shorten the threadmarks list.
Here are some threads that this problem happens: