Re: Send an email (V2) will not allow Dynamic Content
MS is in the process of changing the editor experience on this. Are you seeing a separate dialog with dynamic fields or two buttons to choose a dynamic content list/expressions editor? I'm now seeing the newer expressions editor and have had to click several times on the dynamics content list to get it to show occasionally.

If you aren't seeing the newer experience and aren't seeing dynamic content, make sure you click on the double arrows to switch between advanced and basic entry. Dynamic content tends to only appear in one.