Hello Arifsam,
According to my knowledge, sending actionable message via email is supported in the following scenarios:
The recipient must be an individual, not a group.
The recipient must be visible on the message. Do not put the recipient in the BCC field.
The recipient must have a mailbox on Outlook.com or Exchange Online in Office 365.
And Office 365 Shared mailbox is a kind of groups, which doesn’t support actionable message. This is the reason why actionable message cannot show in the shared mailbox. Here is an article that you can refer to: Send an actionable message via email in Office 365
Regards,
Rick