Pipelines being triggered with Stale Artifacts

Issue

After a Spinnaker upgrade, one or more pipelines is triggered with old/stale artifacts. This can be caught by the build number moving back on the affected pipelines from a bigger to a smaller value (eg. from build # 100 to 20). This behaviour has been observed on pipelines with an ECR and Jenkins trigger. 

Cause

While the cause has not yet been confirmed, the culprit is suspected to lie with leftover stale data in Orca's queue, left in there prior to the upgrade.