delete the cache file manually or with script. PDG node will check the cache file before onPrepareTask(work_item)
That looks like some workaround solution. Especially from the view of just triggering workitem state (Read/Write). I would be surprised that we don't have API control under UI functionality.
In summary – we're working on some improvements to the caching mechanism, which includes making it more configurable. Those changes will be available in the next few days.