I did a CBB installation on my Windows 10 and had to uninstall everything because of a virus.
Now I downloaded the BandLab Assistant again and after entering my login data, Melodyne (which I had marked in the previous installation) appears checked BUT WITHOUT THE OPTION TO UNCHECK.
But in this way, BandLab Assistant does not allow me to proceed with the installation:

So I had to check any other option for the "Install" button to be available:

 
 

The checks reflect what BA has installed based on entries in HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software\Cakewalk\Installers.
 
FWIW, since you already have a Celemony account, you should always use the installer from that account and not bother with the Melodyne install option in BA anyway.

rogeriodec
I did a CBB installation on my Windows 10 and had to uninstall everything because of a virus.
Now I downloaded the BandLab Assistant again and after entering my login data, Melodyne (which I had marked in the previous installation) appears checked BUT WITHOUT THE OPTION TO UNCHECK.
But in this way, BandLab Assistant does not allow me to proceed with the installation:

So I had to check any other option for the "Install" button to be available:

 
 

I had the same problem... Solved by deleting registry entries after uninstalling BA and CbB. You must open "REGEDIT" and manually deleting the "Cakewalk" and "Celemony" entries in "HKY_CURRENT_USER" and "HKY_LOCAL_MACHINE" software folders.
I hope this bug to be fixed soon.

This is a known limitation with the Melodyne demo and BandLab Assistant. The installer for Melodyne that launches from BandLab Assistant initially marks your machine when it installs because it launches from within a container installer built by BandLab. The subsequent uninstaller for Melodyne is Celemony's own uninstaller and cannot remove the check box from Assistant. You can either manually remove a registry key to reset the check box in Assistant, or you can also get the demo for Melodyne directly from Celemony if you need to reinstall it.

Jon Sasor [Cakewalk]
This is a known limitation with the Melodyne demo and BandLab Assistant. The installer for Melodyne that launches from BandLab Assistant initially marks your machine when it installs because it launches from within a container installer built by BandLab. The subsequent uninstaller for Melodyne is Celemony's own uninstaller and cannot remove the check box from Assistant. You can either manually remove a registry key to reset the check box in Assistant, or you can also get the demo for Melodyne directly from Celemony if you need to reinstall it.

And that is already reported to Celemony?
Thank you.