I have a collection on my Aura H2O2 and I cannot get it to list in series order.

There are 9 books in the collection, and the order they are listed in is

0.2
2
2.5
3
4
5
5.5
6
1

I have tried updating the series order for the whole series 3 times, and for book 1 twice. Each time I am careful to make the book(s) is/are highlighted, and select "update metadata in device library. Then I eject the device check the collection, and run it again. The first time I did this, the plugin showed a non-zero result for "books changed" Every subsequent attempt, no books have been changed and the series order persists in being almost perfect, except for having the first (published) book listed last. What am I doing wrong this time?