Was trying to find a solution to new emails not showing but unread number increasing but no applicable articles were coming up. But after hours of trying solutions, I think the answer was to mark some older emails that were marked unread as read. Then the latest couple of days of emails started coming through. This happened when migrating Cox.net emails to Yahoo and then modifying Thunderbird account settings to retrieve them. This email account has over 14K emails from 2014 and later showing in Yahoo Inbox and somehow the Thunderbird Inbox is showing 26K, probably some duplicates, although I have been using the extension "Remove Duplicate Messages". In Yahoo, I made more folders for several older years and moved emails from the Yahoo main Inbox to those various years to cut the size of the Inbox. Any other suggestions would be great for similar situations.