Public sign-only RSA key not restored when importing armored backup file.

[Tim Friske]

Hi,

when I import the armored secret key file to restore the public and
private parts of my own OpenPGP key the secret and public parts of my
primary key and subkeys are restored *except* for the public part of
my sign-only subkey. After the import the pubring.gpg file contains:

1. Certify-only primary RSA key
  (a) Encrypt-only sub-RSA key
  (b) Authenticate-only sub-RSA key

The secring.ggp file contains:

2. Certify-only primary RSA key
  (a) Sign-only sub-RSA key
  (b) Encrypt-only sub-RSA key
  (c) Authenticate-only sub-RSA key

Where is the public part of the sign-only sub-RSA key gone?

When I restore the public key from the secret key with the gpgsplit
program the previously missing public part of the sign-only sub-RSA
key is back again.

Any clues, why not the public parts of all secret (sub)keys are
restored upon import?

Many thanks in advance.

Best regards
TIm