All I can figure is that there was a problem in the transfer or in how it was done.

Here is the link for moving a profile in Windows when installed in default location:

https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

here is the info in brief steps:

1. ensure thunderbird is NOT running on old machine
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media
5. ensure thunderbird is installed on second computer and NOT running
6. enter %appdata% in search window on task bar and press Enter key
7. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
8. start thunderbird and all should be there

David - thanks for your help. The link you sent me is the one I originally used. I took your approach and used the search window. Same result. I used Revo Uninstaller to remove TBird from the W11 box and then reinstalled it. Used a different flash drive to copy TBird on the W10 box. Went back to the W11 box - same result. Local Folders show in the Profile - Mail folder but not when I open TBird. I built the W11 box about 4 months ago - haven't had any problems with it but maybe there is something???? Other ideas???

FIXED IT!!! Did some more investigation. Went into settings - Seems TBird was pointing to the flash drive for the Local Folders - changed it to the correct location - problem solved