Error when trying to locate key via WKD

[Christoph Klassen]

Hello,

I tried to get a key via WKD (using the command --locate-keys), but it 
didn't work as expected. The error message I got was:

gpg: using pgp trust model
gpg: error retrieving 'christoph-klassen at mail.de' via Local: No public key
gpg: Note: WKD uses a cached result
gpg: error retrieving 'christoph-klassen at mail.de' via WKD: No data
gpg: error reading key: No data

But when I use the following link (direct method), it is possible to 
download the key:

https://mail.de/.well-known/openpgpkey/hu/9w5z5jua7mhm8xoha4aixbdx4rotdwm6

I used GnuPG 2.2.19.


Regards,

Christoph