Setting up a master node is not for beginners. A simple typo may be all that's wrong.
My master node is ENABLED and running, but setting up Sentinel and testing give me 19 pass and one fail.
Limited documentation exist and I checked username and pass for errors....so I thought
FIX : a syntax issue. "RPCUSER= " needs to NOT have a space between the = sign and the username supplied.
In the conf file of your server make sure there are no spaces! :
rpcuser=username
rpcpassword=password
Also do not use special characters for username / pass