I have the same problem but I name certain pages after the numeric title of an art piece.
Go here: https://eagleapex.com/digital-prints/
“18”, “1113”, and “3119” all suffer from missing pages.
Also https://eagleapex.com/digital-prints/12/ which is a test page I made that worked fine without a parent. I’m not using a date-based permalink structure, so what re my options?