that doesnt seem to be the issue though the key is fine on 1803 one thing i noticed is the last 3 digits of the Product ID change when going to 1903 which is what i think is causing the failed activation it has been sitting on a key since the 4th July 2018 see image above for what it has looked like since then
not sure what was up with that key slmgr.vbs -upk slmgr.vbs /ipk key resulted in it deactivating then activating again just fine but no digital license slmgr.vbs -upk slmgr.vbs /ipk new ebay key resulted in digital license within a few secs