Is your camera still a child of the CameraRigRail actor? If not, make it a child.
Is your level sequence camera track set to cut to that camera? Camera spawning in a random spot sounds like you might be seeing the player view instead of the camera you’re trying to control.
What I’ve encountered with this is that You must create a camera and rail and then make your rail path. Then make the rail the parent of your camera. Do this BEFORE you open the sequencer. If you create it while it’s open your going to run into issues. Someone mentioned this fix on a youtube thread and it saved my evening and got me out of this road block.