I've waited for the clock to rack up another few hours and see that TCB is still not recognizing when I last connected to the bb. Strangely, posts before about 11:30 a.m. on July 30 don't have the NEW flag. After that, they all show NEW.

It may be significant to mention that the change of color for posts I have read still works properly. I believe that is a function of finding the post in the history file on my PC, so probably not the same process as checking the current time vs last logon time, which I'm assuming comes from reading a cookie on my PC.