Although am setting this as an openSUSE 14.2 problem, I also noticed this
happening on 15.3 so don't believe this is an OS problem.

As recently as yesterday, it was possible to launch YAST2 from the menu, but
now cannot on both a 15.2 and a newly installed and updated 15.3.

At first, noticed trying to install an app using One Click Install on to the
15.3 machine, and the install failed because root permissions not set.

Then, noticed the same problem unable to launch YAST2 on a 15.2 from the
menu... Was able to enter credentials but then failed saying that root
permissions required.

Of course in the case of the 15.2 machine I could get around the problem by
launching from a root console.

This all seems to have happened within the past 24 hours.
In both cases the machines were freshly updated.