And another suggestion: Don't show "green" status, when monitors are stopped.
It seems that I found the issue. Apparently the monitors have been stopped when transitioned to the Free plan, and I was supposed to start them manually (supposedly because I could have had more than 5 monitors - I didn't - and they needed to be started selectively now).
Suggestion: Count the number of monitors, and don't stop them, if they don't exceed 5.
Customer support service by UserEcho