Issue with reordering missions

I'm having trouble manually reordering my missions.

For some of them, they reorder as expected when I drag/drop.

For others I can reorder the item, but when I perform the Drop part of Drag and Drop, it places the item several places further down the list instead.

And for some others, I can't reorder it at all. When I drop the item, the Item Saved popup doesn't appear, and when I reload the page, it's back where it was.

I really need these items to be in a specific order for this experience.

Is anyone else having this problem? If so, how did you fix it?