Drag and Resize Position:Absolute all of a sudden stopped working. What can I do?

While I agree with the others, that absolute positioning should be avoided, there's likely a simple reason why it suddenly stopped working.

You are probably in Live View.

Absolutely positioned elements work as they always have, even in the latest version, but only from within Design View.

Go to Window > Toolbars > place a check by Document > click the small triangle to the right of Live, in the toolbar that appears, and choose Design

Also see this announcement.

https://community.adobe.com/t5/dreamweaver/image-optimization-workflows-deprecation-in-dreamweaver/td-p/11310914?page=1

width="4608" height="3456"

Are you building this for an outdoor stadium jumbotron or average users on average sized devices? 

Ideally, you crop & optimize images in Photoshop or other graphics editor BEFORE you bring them into DW.  

Position Absolute should never have worked in Dreamweaver the way it did. It created more problems than the perceived drag and resize ability. That is why Dreamweaver dropped the ability in later versions.

To find out more, see https://www.w3schools.com/css/css_positioning.asp or Google the subject.