プラットフォームについて: Cloud のみ - この記事はクラウドプラットフォームのアトラシアン製品に適用されます。

要約

Dates are not rolling up to the target end dates in the Advanced Roadmap plan

環境

Jira Cloud

It is to be noted that if the issue is assigned to some sprint in the past, the target end date is picked up from that sprint assigned to the issue rather than the rolled-up sprint values from its child issues.
If the issue never had a sprint assigned, you would see that the target end date has taken its value from the latest of the rolled-up sprints.