Ribbon is not shown when Ribbon Type = Microsoft.Outlook.Mail.Read in VSTO Outlook Addin

I am new to VSTO add-ins and trying to update control on a Ribbon at runtime.

Followed the below steps mentioned in the below article.

https://docs.microsoft.com/en-us/visualstudio/vsto/walkthrough-updating-the-controls-on-a-ribbon-at-run-time?view=vs-2019

But when I changed RibbonType property to Microsoft.Outlook.Mail.Read from Microsoft.Outlook.Mail.Compose Ribbon is not being shown while reading the mail messages.

Any help would be highly appreciated.