How to add formatting in zoho.cliq.postToUser(...) message?

How to add formatting in zoho.cliq.postToUser(...) message?

In a CRM Deluge function, I'm trying to use the message formatting guidelines given here:

https://www.zoho.com/deluge/help/cliq/posting-to-zoho-cliq.html#message-formats

My message is:

message: #Title text.

The result in Cliq is:

#Title text.

(no large heading formatting was applied)

Please advise.

Thanks

Clark