After updating xkeyboard-config to version 1.1 the key switch no longer works. Downgrading back to 0.9 solves the issue. Reproducible: Always
If an update of a non-KDE package breaks KDE, why would you file the bug against KDE? Especially when there are four other bugs for the same issue in several other applications? Re-emerge xf86-input-keyboard and if that doesn't fix it, do that for libX11 and xorg-server, too. That should fix it.
The problem is not xorg-server, xf86-input-keyboard, or even kxkb. The new version of xkeyboard-config does not create the symlink /usr/share/X11/xkb/compiled --> /var/lib/xkb Creating the symlink manually fixes the problem as per bug 194026 *** This bug has been marked as a duplicate of bug 194026 ***
*** Bug 194294 has been marked as a duplicate of this bug. ***