Just to inform you I have reported this issue to the development team to investigate further as it is unusual that the artifact is spawning in another location other than underneath the water near the waterfall.
If you do experience this issue and are unable to find the artifact at all after the checking the whole area near the waterfall with your Odin sight then please let us know in this thread and provide a video demonstrating the issue.
In the video we would need to see you check the whole area using your Odin sight and show your inventory to show that the artifact hasn't already been collected.
I would recommend uploading your video to a video sharing platform such as YouTube, you can then copy the URL link into this thread.
Can you also ensure that your latest save is uploaded to the cloud. If you are unsure how to do this there is a support article that you can check here.