Mystery of missing email!? - pst/.ost files, IMAP, export/import, Outlook 2012 to 2021

[d_j_h]

March 2023 and a major OS 'CRASH!' caused by a Windows 10 update I managed to quickly back up our email files, .pst & .ost, from Outlook 2012. As that crash became a digital mess I ended up wiping the drive and doing a reinstall of Windows 10 for a clean start. I then started chasing up software for re-installation and in the process decided to also update a few things, including to Office 2021, previously 2012. I then used Outlook 2021 to connect to our email account, the thread I'd started previously to this one. It was slow, but eventually, thankful to some help given here, all email showed in all folders.

Next I tried to import the saved .pst file, which I'd moved to the Outlook file the Outlook 2021 search took me to (C:\-). I clicked on it and 'et voila!' it seemed to work. Inbox seems to have filled, not sure if it was complete, but looking promising. Then, horror of horrors, as other folders showed nothing else did - every other folder was empty:

* Sent - should have considerable content...
* Trash (Deleted) - should have considerable content...
* Archive - likely something, though a new folder not in 2012.
* Drafts - there should have been a few items there.
* Spam - always something...

All those boxes were empty!? AND - NO CONTACTS!?! I've done this kind of transfer before when changing work/home computers or upgrading Windows or Outlook, import/export of a .pst file, and previously I've not had any problems.

    Is there a solution? IS there a conflict with the newer OS and/or Outlook? I still have extra copies of these files backed up. Do I need to install and open an older version of Outlook to get full access? Can that be done, having two different Outlook programs on the one PC? Here's hoping there's an answer. All out families and friends emails are in that contact list, and sadly I've not backed them up to paper copies, just several copies of the old Outlook files, .pst/.ost... Fingers and toes crossed, and prayers while losing some sleep over this...

[d_j_h]

Confusions over the missing addition, I forgot to reconfirm, in those past exports/imports between different OSs and versions of Outlook, all folders were retrieved with content, along with contacts...

[d_j_h]

Diolch/Thanks for the response, contributions, much appreciated...

Weird, I just responded to this with information and a little history and "POOF!" it's gone!?  I'll try a recap?  Hopefully this time it will take?

Some of the history is above.  I've been here before and without any problems, all folders showed with their expected content, including our contacts, and this has happened several times across several OSs and versions of Outlook.  The last few times were when upgrading to Outlook 12 and when upgrading to Windows 10, with no losses.  I am considering trying another option, to install an old version of Outlook and see if that will work, and if it does then backing up email as individual files instead of trusting things to the pst file.  I have been doing quite a bit of reading on this online.  I'm still not quite undrestanding the differences between pst and ost files, but will do more reading and hopefully clear away some of that ignorance on my part, wanting to understand.  I keep coming across options/software for reading ost files, which while it is an Outlook file Outlook 2021 doesn't recognize.  It's not a file I've used before, though I did back up both pst and ost files before this recent digital mayhem that lead to the reinstallations and these two recent entries/queries here.

[Gondola]

A PST file from Outlook 2012 wouldn't automatically save mail folders other than the Outlook 2012 Inbox. Contacts from Outlook 2012 should have been saved. From Outlook 2013 onwards when that's set up for IMAP accounts then synchronised mail messages are cached in the OST file.  

Your description matches what I'd expect from a PST file from Outlook 2012.