Please send an email to the jenkinsci-users mailing list for a general investigation like this. In your email, please add details about whether this was working for you previously, and if so, with what version of the plugin and Jenkins, what version of Jenkins you are running, what OS you are using on the Jenkins master and the agent being used by the shell step, how the agent is configured, what you have tried (did you attempt to change HEARTBEAT_CHECK_INTERVAL as suggested by the error message?), whether the Jenkinsfile has changed recently, etc.
In the future, please include log output via a site like Gist or Pastebin, or attached as text files here, not screenshots, so that we can search them.
I am going to close this issue for now, if it looks like there is a bug after you provide more info on the mailing list, we can reopen the ticket, so please do not open another ticket for your issue.