Hello,
I believe I found a bug with gpg v2.3.6, as it no longer works with ssh. v2.3.4 worked using gpg keys for ssh authentication, but 2.3.6 does not. It appears to ignore the keys altogether, even with SSH_AUTH_SOCK pointed to the right place.
This is the first time I've ever submitted a bug report, please forgive me if I haven't included or specified the issue well enough. If you need more information, like logs etc, please let me know and I will provide.