Hi Ran,
Seems like a known issue the fix is suppose to export the key from the working server with exportable keys and import on the Windows 2012 Server.
Solution: Import the .pfx into a newer version of Windows (Like Windows 10 or 2016) . This is important. While you import process, mark the certificate as exportable. This allows you to export the certificate afterwards with the older Triple-DES-SHA1 algorithm or/and with no password to protect the key.
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