I’m running DSM 7.0.1-42218 over here, and do not experience the problem you’re describing.
Did you also update Docker itself in the Package Center? I’m running 20.10.3-1239.
Also, is the screen (browser window) really completely blank? Or do see just the Duplicati menu, but all tasks seem to be gone? (I’ve had this happen to me a couple of times before, was unable to reproduce it though.)