I checked these threads (which I was the last to post in), let an hour pass, came back and they were all marked as unchecked... so I checked them all again (even though there were no new posts in them), closed my browser for a little while, came back and they appeared as shown in the picture (unchecked, yet again)...
If I check them, then return to User CP, they are marked checked... but if I close the browser and return while they are still in the "Subscribed Threads with New Posts" area, they will be marked as unchecked again!
The only way I can find to remedy this is to use the forum command "Mark Forums Read"... but that marks ALL the forums read, not just my subscribed threads! (I don't want to do that)
It's a little aggravating to see threads where I am the last poster marked as unread after I have checked them multiple times over the course of an hour or more!
Each thread in the "Subscribed Threads with New Posts" area has a the - Reply | Unsubscribe - options... would be great if there was a "Mark Read" option there as well... would solve the problem!
(and yes, I know this is kinda petty)