Why aren't the project plan date changes saving?

Summary: When trying to change project planned dates within project execution management, the date changes I make aren't saving when hand typing in the date change. Any idea why?

If I double-click and select the date from the calendar, the new date I choose will remain. If I double-click on the date and hand-type the new date, the date change doesn't save and reverts to the original date. Is there a reason why the date's only changing when selecting it from the calendar and is not changing when manually entering it?

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