@plettich Thanks for confirming!
I’ve done some web crawling, and it seems, indeed, the keyservers out there disagree, weather our key exists, is expired, or is valid:
./check_gpg_keyserver.sh 1B07204CD71B690D409F57D24ABE1AC7557BEFF9
##### remote keyservers
hkp://pool.sks-keyservers.net : pub rsa2048 2016-09-25 [SC] [expires: 2021-04-18]
keys.gnupg.net : pub rsa2048 2016-09-25 [SC] [expires: 2021-04-18]
pgp.mit.edu : pub rsa2048 2016-09-25 [SC] [expired: 2019-09-19]
uid [ expired] isv:ownCloud OBS Project <isv:ownCloud@build.opensuse.org>
hkp://keyserver.ubuntu.com : pub rsa2048 2016-09-25 [SC] [expires: 2021-04-18]
hkp://keyring.debian.org : --
zimmermann.mayfirst.org : pub rsa2048 2016-09-25 [SC] [expired: 2019-09-19]
uid [ expired] isv:ownCloud OBS Project <isv:ownCloud@build.opensuse.org>
pgp.surfnet.nl : pub rsa2048 2016-09-25 [SC] [expires: 2021-04-18]
pgp.key-server.io : pub rsa2048 2016-09-25 [SC] [expires: 2021-04-18]