Some DNS providers do not support underscores in zone file entries, however an underscore is required in some DNS entries outlined in the Whitelabel process.

If your provider does not allow you to use underscores, you may need to consider changing DNS hosting provider if you want to take advantage of the Whitelabel feature.

Alternatively, disabling Automated Security when Whitelabeling will remove the need to set up the CNAME records with underscores in them that can cause this issue initially.