The guide doesn't work. (at least for me)It's probably for old versions or for imported addresses.
The only way one can verify/sign is by importing addresses. (Haven't really tried importing one to confirm,but it's what I've concluded going around their faq/help/etc.)
The new addresses generated by this latest version of blockchain.info cannot be verified/signed. It's still unsupported. No idea why. Or if this will change.
Imported Addresses Not backed up by your Recovery Phrase. Transfer into a wallet to secure funds.
Transfer All
Meaning they wanna get more funds while we do use our old adress, i do hope they allow us to sign messages from new adress and stop being greedy to the point to charge us to transfer funds between adress since has no costs for them.
I have same wallet version. So I imported one of my used address (that is from same wallet id) only to see if I could sign it. But there is not this option. Click to more options right from imported address and only options are: archive, transfer, spend. Moreover, they claim in their support that I can sign an imported address /hc/en-us/articles/210353833-What-is-message-signing-and-how-can-I-do-that-]https://support.[Suspicious link removed]/hc/en-us/articles/210353833-What-is-message-signing-and-how-can-I-do-that- this is not working. Looking forward to see what happens in newer versions.
Look the imported adress if belongs to the last version of blockchain.info you will be able to sign a message, just the new adress of the new wallet arent able to sign a message at the moment. Im able to sign any message from old adress, just follow the steps if its an old adress if its a new adress you wont be able to sign messages.