You didn't explain how you restored local folders. From your sentences, it appears that was done separately from transferring your email account. However, my suggestion is to - exit thunderbird - in File Explorer, copy the Local Folders from old Profile to Local Folders in new profile. Usually, that is sufficient.

Thanks for the response. I believe that what you suggested is what I did. I copied my Thunderbird profile (C:\users\<me>\AppData\Roaming\Thunderbird\Profiles\<my profile>\) from the old computer to the new one. This included <my profile>\Mail\Local Folders\<all folders and files>. I then installed Thunderbird. As I noted in my original query, Thunderbird successfully connected to my gmail account. In the Thunderbird menus, I went to Tools->Account Settings->Local Folder->Local Directory and specified the path to <my profile>\Mail\Local Folders with the results described in my original query.

As noted previously, the total size of the files in Local Directory is about 500 MB whereas I was expecting it to be greater than 10 GB

I encourage you to look at the old profile to confirm that the 10 gig folders are there. With thunderbird not running, I suggest repeating that copy and then confirming in File Explorer that the 10gig data is in Local folders

From your most recent post, it seems you are using two profiles, one for your email and one for the local profiles. Just an FYI: if you're not using the same profile, you can store the folder anywhere. The possible benefit of same profile is that any documented backup procedure will get it all. With two, you have to remember to handle the Local Folders. (NOTE: This paragraph is just a comment: has nothing to do with whether you're seeing all the messages.)

Thanks again for your reply. My old and new profile are identical. I simply copied the one on my old computer to my new computer. The reason I think the total size of the files in the profile's Local Folder should be more than 10 GB is that that's how much space the emails take in my gmail account. Also when I examine the emails of my regular correspondents (each correspondent having their own subfolder in Local Folder in Thunderbird), they all stop at around on the same time over five years ago. None of the emails in the Local Folder is more recent than five years ago. None of the subfolders I created more recently than five years ago currently exists.

Were those missing local folders in the old profile? If so, they should have copied with other folders.

No, the missing local folders were not in the old profile. But those folders along with all the missing emails were being displayed in Thunderbird on my old computer.

Somehow Thunderbird on the old computer was displaying more folders and emails than were in the old profile. Thunderbird must have been getting this data from some place other than the old profile. There was only one profile. Is this possible?

No, the missing local folders were not in the old profile. But those folders along with all the missing emails were being displayed in Thunderbird on my old computer.

Sounds to me like your old computer has a disconnect between the files and folders in the profile folder and the foldetree.json file that caches and displays folders in the folder pane.

But given you have already said you changed the account folder on your new machine. (Something I really do not think anyone should do. But there does appear to be a cottage industry in doing so.) You might want to look at what you have it set to on your old computer. My guess is something completely different to where you are looking.