If Jenkinsfile in a multibranch project "Folder/Repo" runs discoverGitReferenceBuild defaultBranch: 'release/1.41', then the Forensics API Plugin tries to find a job named "Folder/Repo/release/1.41". However, the branch "release/1.41" actually corresponds to the job "Folder/Repo/release%2F1.41"; the slash is encoded as "%2F". Because the name does not match, the Forensics API Plugin does not find the job.
[ReferenceFinder] There is no such job - maybe the job has been renamed or deleted?
(The 'release/1.41' string is not actually hardcoded in the Jenkinsfile.)
It looks like Forensics API Plugin 0.8.0 constructs the "Folder/Repo/release/1.41" string here: https://github.com/jenkinsci/forensics-api-plugin/blob/b1101561ba19c172d561704ae445a146c521cf88/src/main/java/io/jenkins/plugins/forensics/reference/ReferenceRecorder.java#L145
The Branch API plugin has a NameEncoder class that encodes the slash as "%2F".
I could perhaps work around this by running discoverGitReferenceBuild defaultBranch: 'release%2F1.41' instead, but I suspect that would break later if the Forensics API Plugin starts asking the Branch API which job corresponds to the specified branch. discoverGitReferenceBuild referenceJob: 'Folder/Repo/release%2F1.41' seems a safer workaround, although more complex to implement.