mohlo by pomoct:
https://github.com/osxfuse/filesystems/issues/1

SSHFS tries to be smart and matches your remote user's uid/gid with your local user's uid/gid. This suffices in most cases but in your case your remote user just belongs to group11 and group12 but has a different gid. That's why SSHFS cannot associate group11 or group12 with your local gid and you are getting the permission denied error.

Here is how to fix this: You need to call sshfs with the option defer_permissions. defer_permissionsdisables local permission checks and forwards all requests to the remote server (as in the SSH case above). Since the server knows that you are allowed to access the folders you will no longer be locked out.

If you call sshfs from command line just add -o defer_permissions. If you use Macfusion put -o defer_permissions in "SSH Advanced > Extra Options".