In another thread FixB has posted the same problem I am experiencing. I now longer see a circle indicating a note in the Activities menu (calendar view). It was back on the 6th Feb that I last see an entry on my activities log, even though notes are visible via the standard Notebooks route.
Now, since then I've had a replacement pen supplied, and the app has been updated. Generally we're slowly improving, but I also find this activities route VERY useful. Is this still working for others on the latest version of the app (and firmware)?