I was unable to post a question, reply or even edit my profile for over a month. Microsoft support took that long to send me this workaround.
After following this process, I was able to gain access to the forums.
This is an exact copy of what Microsoft Support sent me:
2. Sign In (with the account which is giving problem)
3. Select preferences from on masthead
4. Select classic version, save, takes back to previous page
5. Scroll down to community content section
6. Your display name shows up on below community content section, looks like below
7. Click your display name, takes to edit page. Edit display name and save, looks like below
8. Re-login from Forums application (if still seeing the issue, wait for couple of hours and retry again).