Cannot decrypt messages sent via DeltaChat using Mutt

Hi,

when I try to decrypt messages sent using DeltaChat I cannot decrypt them on the other side using mutt (key IDs replaced by “…”):

[2019-08-05 17:10:45] …/…/pgp.c:930: mutt_mktemp returns “/tmp/mutt-…”.
[2019-08-05 17:10:45] mutt_pgp_command: gpg --status-fd=2 --passphrase-fd 0 --pinentry-mode=loopback --no-verbose --quiet --batch --output - /tmp/mutt-…
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] ENC_TO …1 0”.
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] KEY_CONSIDERED … 0”.
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] KEY_CONSIDERED … 0”.
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] DECRYPTION_KEY … …u”.
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking "[GNUPG:] PLAINTEXT 62 0 ".
[2019-08-05 17:10:45] PLAINTEXT encountered outside of DECRYPTION. [2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] PLAINTEXT_LENGTH 268”.
[2019-08-05 17:10:45] PLAINTEXT encountered outside of DECRYPTION. [2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] NEWSIG”.
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] ERRSIG … 1 8 00 1565009491 9 -”.
[2019-08-05 17:10:45] pgp_check_decryption_okay: checking “[GNUPG:] NO_PUBKEY …”.
[2019-08-05 17:10:45] Decryption failed

Is there some bug or some kind of misconfiguration?

I can pipe the whole e-mail into “gpg -v” and get its contents together with the following message:
gpg: public key is $A
gpg: using subkey $A instead of primary key $B