Is FR24 incorrect then (Check aircraft reg. and then flight plan for next couple of days) N48127 (this morning's a/c which has gone tech) has only recently been switched to show departure out of AMS tomorrow as UA71.
Just enter N48127 in search box on FR24 and info will appear. As with other searhes.
What is your source that indicates it leaving NCL and tomorrows Inbound delayed?