OpenPGP on Thunderbird 128.7.0esr

Hi -
I’m running 6.12.12-2-MANJARO on Plasma 6.2.5, and have a few questions about OpenPGP communication on Thunderbird 128.7.0esr, and also using Kleopatra.

I have a few email addresses I access on Manjaro (via Thunderbird), and a Windows platform with a separate Outlook email there, too.

If I send from personal runbox.com email to personal email gmail using Thunderbird, its OpenPGP implementation encrypts and decrypts just fine.

And I can encrypt/decrypt using Kleopatra from personal runbox email to Outlook on the Windows platform.

But encrypt/decrypt from Kleopatra to Thunderbird doesn’t work. I guess they used different standards? I thought they were interoperable, but I guess not.

Your comments / suggestions are welcome.
Thx

Here’s a good place to start for all things Thunderbird;

Any of the following links might potentially be useful;

Regards.