Ah OK, understood. Well still, for me, it has not been an issue and I have not seen any deviation from the old way over the last number of weeks.
When I log in all the new threads at the top are Bold and all older read threads are still Roman. If I click in on a new thread at the top and then navigate back out using the correct link at the top (not the back button) the new thread will now immediately be changed to Roman.
If I log out and back in, it will still be Roman and all new threads underneath it will still be Bold and all read threads will still be Roman. Hours later this will still be the case when I log back in.
Or if I stay logged in and was reading a thread, and then left for ages while still reading it, and then navigate back out, all is still as I would expect it.
So it does appear to be only affecting some? That's why I'm suggesting to name the browser in use with each case presented.
G.