Project for the web - Sync Issue

We have the recurring issue within our roadmap that we cannot resolve. We have deleted, recreated the entry in the roadmap  but the issue remains. Within the flow view in powerautomate we can see an fail reason of Action: Startdate Failed but do not know what this means. We think that it is when checking the flagged items to display in the roadmap and can see no issue with the data. Can anyone provide advice on this?