And there it is.
For a long time there was a bug where it would not work for newly created characters until you had changed it. i.e. it would show as the default "7 days", but not work. This was fixed quite some time ago, but it probably only fixed things for characters created after the fix went live.
Try setting your autopay to a different setting. Or turning it off. Wait a day, then turn it back on. That used to fix things for characters who were affected by the bug.
