This ticket can be closed. No further issue with email decryption after applying the provided patch

I've tested the fix and so far I found no problems with decryption and email rendering.
If you want I can report back here, after using GgpOL several more days testing the fix in day-to-day usage, and then if everything is fine we can close this ticket.
Thank you very much for your time.

To sum up: Outlook can't decrypt a reply, although it can decrypt a direct email from the same sender.
Another thing I just noticed: once Outlook receives the reply (the one it can't decrypt), I can no longer move emails to other folders. If I deactivate GpgOL plugin, I can move the messages again.
Can I pm you the saved message ?

The connection is a POP3 connection. Email server is a 3rd party email service provider. I doubt is an Exchange server (I believe they run a Linux server).
Switching to a different mail and back makes no difference - no email body displayed for the encrypted email.

I have some progress and a step back.
Turns out that one of the installed plugins was causing the problem: "PDF Converter 7.1 Outlook Add-in".
I disabled all plugins (except GpgOL) and then enabled them back one by one.
With PDF Converter add-in disabled I'm now able to see the decrypted email body (sent from myself).