After performing a build history purge (and reset build number to 1) using the purge job history plugin the stage view shows the stage view from the previous build.

Looks like its a similar issue to JENKINS 36865 and the below workaround (listed in the comments session) resolves the issue.

import com.cloudbees.workflow.flownode.FlowNodeUtil

FlowNodeUtil.CacheExtension ext = FlowNodeUtil.CacheExtension.all().get(0);
ext.getRunCache().invalidateAll();