It's important to note here that the path to the attachment is from the master.
Attachment – Type a pathname to locate a file on the network to attach to your email. You must type the pathname from the perspective of the master, not from the perspective of the Tidal Web client.
It would be useful if it could be from the perspective of an agent, but this is what we get. So if you can navigate to the file you want to attach when logged in to the master you can attach it to a message sent by email action.
Actually 3 hrs before, I tried providing the path for the attachment in Email Action. Didn't get the mentioned file but received the mail with subject & body message. Upon reading I found that we need to add mention the path in master as mentioned by you(Brain's mail). Currently I am using Tidal Web Client and have access only for this.
Could please elaborate a bit more about how to add the path in Master or share any links to know about it.