I have created a custom column of the type "Choice" and then a view which will sort by that column. Surprisingly, one folder always gets sorted last and not with its "siblings" which have the same value entered for that column.
As you see, the last folder, whose name starts with "Om", should be up on top with the others of type "Planet".
This only happens when I open the view. When I sort the column manually, the sorting works as expected. You can see that the "Om" folder has moved up as the last of the planets, even though it is still sorted after the "Si" folder (so not alphabetically).
All folders here are from the same custom type, which allows me to assign the "Usage directions" and "Celestial body" columns, but are else all normal. The properties of the "Om" folder look just like the properties of any other folder shown here.
The sorting settings for this view are below. The "IsPinned" property is set to "No" for all folders here, including the misbehaving "Om" folder. The problem also persists if I check the "Sort only by specified criteria" box.
What is wrong with this sorting, and how do I get it to behave normally?