OpenSSH has replaced "curve25519-sha256@libssh.org" with "curve25519-sha256" (https://github.com/openssh/openssh-portable/blob/master/kex.h#L63). The current code generated by ssh-analyzer.pac only looks for "curve25519-sha256@libssh.org". If both client and server use "curve25519-sha256" the code generated in ssh_pac.cc will produce "ssh_unknown_kex_algorithm" causing the rest of the SSH analysis to fail (e.g., authentication) since the state never gets updated. I'm not sure how to change the BinPAC code but the fix in the code produced from BinPAC in ssh_pac.cc is the following:
It appears this has been fixed in the git repo. This can be closed