There seem to be various issues with this sample.
metadata.version is set to a value that is not reasonable. OCSF Version 7.5.0 does not exist.
https://github.com/ocsf/examples/blob/12802e239cc29016d267549e476d563b0b26bcc8/Findings/Security%20Finding/IBM/QRadar%20SIEM/offense.json#LL65C1-L66C1
severity_id - is a required property but is not set on the sample.
There may be various other issues but I stopped looking into using the sample after these 2 issues were uncovered. Just wanted to document this here in case someone else stumbles on this.