Transfering a secret key to a hardware token did not work as documented.
Hardware tokens that are reported to not work:
* Nitrokey Start
* Nitrokey (Pro 2)
Move was done on the command line.
Thunderbird is also used.
* gpg -K lists shows hint about smartard (as expected)
Symptoms:
* No smardcard icon in Kleo (expected: icon is there)
* secret key can still be exported (expected: cannot)
The documentation
https://www.gnupg.org/documentation/manuals/gnupg/OpenPGP-Key-Management.html#index-keyedit_003akeytocard says
The secret key in the keyring will be replaced by a stub if the key could be stored successfully on the card and you use the save command later.
Reported by a user with GnuPG 2.2.25 on Windows (via Gpg4win 3.1.14).
According to the user it worked in April/May, which would habe been Gpg4win 3.1.11 with GnuPG: 2.2.19. The bad behaviour was reproduced on both machines.