/bin/bash -c "cd "/cygdrive/d/CI/jenkins-ssh" && java -Djava.util.logging.config.file=/cygdrive/d/CI/jenkins-ssh/logging.properties -jar slave.jar"
The command line is not correct but does not matter because "/bin/bash -c" does not return any error, it should return at least a syntax error, I do not know what happen on your environment but it is not related with the SSH Slave Plugins it is something in your sshd configuration, on your user login, on your environment initialization files (.bashrc, .profile, ...), or your default shell, I bet that if you put
on your command prefix you would see nothing in the console output.
You could try to execute a command using the ssh command line, probably it fails
ssh USERNAME@AGENT_HOST /bin/bash -c ls
try the same but with -t parameter, it should work
ssh -t USERNAME@AGENT_HOST /bin/bash -c ls
I recommend you to check a really good comment from Ben Langton at https://wiki.jenkins.io/display/JENKINS/SSH+slaves+and+Cygwin that explains all the steps that you have to make to configure OpenSSH.
If you need more help, try in the jenkins user group.