While doing some tests I found an issue (this is a restarted build that was restarted from the "Static Analysis" stage)

The state of non-parallel stages is being correctly reported as "NOT_BUILT" while the state of the Parallel stages is "FINISHED"

The jenkinsfile used in the example above is: https://github.com/NicuPascu/app-store-demo/blob/longer-pipeline/Jenkinsfile