Hi All,
I just wanted to follow up to this post as yesterday the same exact problem happened to my colleague after recent service release update.
It is quite possible that, as @Alain mentioned, some program (perhaps another instance of Rhino, perhaps a text editor / script editor) was using the libraries during the update installation.
When looking in the %appdata% folder for the rhinoscript libraries, userinterface.py is present and the various rs.Get methods within it as well. However, when accessing the method help through the left sidebar of Python Editor in Rhino, none of the methods were present under rhinoscriptsyntax, nor did they autocomplete when typing in the editor.
The solution was simply to make sure no programs are running which could be locking those files and running the service release update installation again.
Everything then works as expected.
-GM