Hi.
I have fresh updated: my Elements disappeared once the PRO was installed, even though I had Elements11.
I suggest you to save all your projects before to proceed.
RGDS
PS: Please remember that you need the USB key for the PRO as well.
I would recommend that you let Cubase pick its default installation directory. It makes a new copy of all settings in a folder named after the product, e.g. on Windows
C:\Users\username\AppData\Roaming\Steinberg\Cubase 10.5_64, and properly updates all your settings. For me, this has worked for years and it makes it easy to back up all the historical versions of settings etc.
ADDED: I should say that I have only ever upgraded from “pro” to “pro” if that at all affects any of this.