The problem appears if you move to IE11, which happens if you upgrade from Win8 to Win8.1.
If you stay on Win8, highlighting will work.
If you are on Win7 and upgrade to IE11, the problem will also be present.
This may work: http://stackoverflow.com/questions/2004 ... 11-to-ie10
But I recommend to be patient for a few days and wait for the new version which will solve the issue.
Yes, we plan to release a new version of the Beta, hopefully in the next few days.
No, I am running a standard Win8.1 upgraded from Win8 configuration and I had the same problem.