Stopping a running PipelineRun via Web GUI does not work in RHOCP 4

Issue

• When clicking stop to cancel a pipelinerun in the web console, the pipelinerun does not stop.
• Stopping a PipelineRun works fine via CLI but not GUI.

• For all PipelineRuns while stopping a running PipelineRun via Web GUI results in below error in the JavaScript console of the browser:

  consoleFetch failed for url /api/kubernetes/apis/tekton.dev/v1beta1/namespaces/cluster-ops/pipelineruns/ldap-sync-xxx a: admission webhook "validation.webhook.pipeline.tekton.dev" denied the request: validation failed: invalid value: PipelineRunCancelled should be Cancelled, CancelledRunFinally, StoppedRunFinally or PipelineRunPending: spec.status at https://console-openshift-console.apps.example.com/static/main-chunk-2053c1388568c1c78c80.min.js:1:164843 unhandled promise rejection: a: admission webhook "validation.webhook.pipeline.tekton.dev" denied the request: validation failed: invalid value: PipelineRunCancelled should be Cancelled, CancelledRunFinally, StoppedRunFinally or PipelineRunPending: spec.status a: admission webhook "validation.webhook.pipeline.tekton.dev" denied the request: validation failed: invalid value: PipelineRunCancelled should be Cancelled, CancelledRunFinally, StoppedRunFinally or PipelineRunPending: spec.status at https://console-openshift-console.apps.example.com/static/main-chunk-2053c1388568c1c78c80.min.js:1:164843