ATP Scan In Progress when attaching document to email

[Jason Beckett]

In my test tenant I have the "default" office 365 configurations including the Safe Attachments policy which is currently set to dynamic delivery. I've noticed that when attaching an email in Outlook I'm getting the "ATP Scan In Progress". My understanding is that Safe Attachments

[#2]

Your question seems to be cut off, but the "ATP scan in progress" experience is the expected behavior when dynamic delivery is used.

[#3]

That is the behavior when attaching documents through the outlook client when sending? Every article I have found so far describes dynamic delivery as delivering the message to an EOL mailbox while holding the attachment until scanning is complete then releasing the attachment to the recipient.