Behavior regarding fixing the positional relationship with the camera

Thank you for your message.
I created a separate empty game object from the player, and checked the “Fix position relative to camera” option in BaseSettings, thinking it would keep it fixed on the screen, but it inexplicably moves.
Is this a bug?

Perhaps you could consider adding an ObjectMountTarget node below the UI node, and then place the object you want to position under the ObjectMountTarget?