New installed and activated Cubase 10.5 LE can not find e-license to upgrade from Cubase 9 Elements

Yes, that is the same one I received, except mine was for AI. It is an UPDATE to an existing license so you need to have an existing license (LE 4 or newer) to update FROM. If you look in your “My Steinberg” and you registered the license when you first activated it, you should see a link to “reactivate” the license. After you go through that procedure and have an actual license on the eLicenser, you can enter the update activation code and it should update it to LE 10.5. It worked for me (I also had to reactivate the AI license because I actually use Pro and didn’t reactivate the AI license last time I wiped and refreshed my PC).