What runners are you using to run the jobs in your workflow? Self-hosted runners or GitHub-hosted runners?
If you are using the self-hosted runners, please check whether the needed self-hosted runners are Online and Idle status.
If the self-hosted runner is Offline
status, you need to startup the runner on the machine where the runner is installed.
If the self-hosted runner is Active
status, this runner is being used. The new triggered jobs need to wait for the available runner.
To view more detailed information about self-hosted runners, you can reference the official documentation below: