We've recently instituted some further changes to the specific HTTP headers used to prevent this issue, and far as I can tell it should be working fine now.
You'll need to clear your browser cache first to ensure old cached versions of the forum pages aren't interfering. This is one-time-only, as from then on the current set of headers should prevent the forum pages from being cached again.
Please let me know whether this fixes the caching issues for you or you are still experiencing them.

Now it works perfectly, good work!

Confirmed!

Works for me, too! Thanks a lot!