Error: This OpenPGP key is not usable. (Could not find primary userCould not find primary userCould not find primary user)

[martgil]

Description:

A user reported that an error saying This OpenPGP key is not usable. (Could not find primary userCould not find primary userCould not find primary user) appears when opening a secure email (encrypted + signed) message they received. Though It doesn't interfere with decryption / signature verification.

Email that reproduces the issue: https://mail.google.com/mail/u/flowcrypt.compatibility@gmail.com/#inbox/FMfcgzQfBGWxXqwWwLSlpDRjKCtzlwhN