Below is a bug report. I hope it is helpful.
This is an error that I first noticed today, January 5.
Clicking on the list navigation arrow in an attempt to see the previous set of 20 discussions (i.e. page 2) results in an error message.
Though the error message indicates that the source of the issue could be that I am logged out, all other forum functionality continues to perform as expected without requiring any re-login.