Question Outlook 2021 Personal folders not included when exporting...

The user is trying to move Outlook personal folders to a new laptop, but only a few folders are moved when using Outlook 2021.

Backstory:

The user (a colleague), has Gmail for around 14 years, but uses Outlook to manage emails.
He has been creating hundreds of personal folders in Outlook throughout the years, but on Gmail there are only a dozen of them. It appears at one point in history (2012), Outlook and Gmail stopped synching.
He has not been checking Gmail for years, so until now he realizes the discrepancies between Outlook and Gmail.

Since exporting and importing (.pst) is not getting all the personal folders, does anyone here knows of another way to move personal folders to a new computer?
 
Copy the .pst in question from old to new system. This is the way it's been done since the beginning of time. If the folders do not appear then they do not exist.
The folders do exist and they do have content on them,... I have seen them.
Yes, I also though that copying the .pst was supposed to do it, but it does not.
Only a few folders, the ones that also appear on Gmail, are transferred.
 
If that's the case then you need to run a repair on the .pst.
https://support.microsoft.com/en-us...-and-ost-25663bc3-11ec-4412-86c4-60458afc5253

If you still don't see those folders then they never existed in that file to begin with or were deleted by the rebuild/index process due to file corruption. If this .pst dates from Office 2004'ish then there is a 2GB hardcoded file size limit, at which the file is lost forever if even a single character is added.