Hello @ThoKl Thank you for your post and for letting us know more about your experience with the new community so far.
I have identified the problem you are facing, indeed you should go to "Forum" and then filter by the Label on the right, however, the feature "Most viewed" should be working regardless. This is the first week of our new Community so we're still fine tuning these details based on your feedback - so thank you for giving us visibility of this issue.
I have escalated this issue with our Support team and will get back to you with a solution shortly.
Best regards, BeaCampos.