Update: After a reboot, Dorico ran as expected. I applied the two updates and, apart from not being able to see recent files, I seem to be back where I was.
I was concerned when I noticed that, when updating, Dorico wanted to install a “Generic Lower Latency ASIO Driver” and I disallowed that in case it messes with my Samplitude/RME setup with which I am quite happy, and also because I hardly ever use the playback facility of Dorico. Does anyone reading this know whether this driver is JUST for Dorico, or used by other programs? If just for Dorico, I will feel happier in installing it; but I am suspicious that Steinberg expects one to use its own products for all audio work and could care less about compatibility with Samplitude. 
David