sgolas writes "This problem is getting worse. I saved my profile and un-installed Thunderbird and installed a fresh copy with no addons. It seems to occur when messages are filtered as they are retrieved from the servers. The messages stay in their inbox. If I re-apply the filters to the inbox, the messages are moved to the correct folders without error. "

Does the problem go away if you start *Windows'* safe mode with networking enabled?? - win10 http://windows.microsoft.com/en-us/windows-10/change-startup-settings-in-windows-10

Problem exists in safe mode with networking. I thought that it might have to do with multiple messages but only one downloaded while in safe mode and it failed to get filtered correctly. Even when I run the filters manually, I can see the size of the folder but the number of messages and unread is empty until I click on the folder. I have noticed an error console and a logging option in the filter file should I turn on filter logging?

See attached.

Does problem go away if you have started Thunderbird in safe mode per https://support.mozilla.org/en-US/kb/safe-mode ??

Or what happens if you open the Food Network folder in a new tab (right click the folder and pick open in new tab), and wait for a filter event to occur?

As I stated above, the problem doesn't go away in safe mode. I included Food Network because that was the one that failed in safe mode. It typically fails on multiple folders. I have been using first Netscape then Thunderbird for years. I have three pop accounts and two imail. I have all of them configured so that I do the message retrieval at my convenience. On a quiet day, I can receive 25 messages at once. I can't possibly predict which folders to hold open when I check for new messages.

What addons do you have installed? They are listed at help | Troubleshooting