Comment # 1 on bug 973724 from Wolfgang Bauer

Sounds like https://bugs.kde.org/show_bug.cgi?id=359460.

We added the fix to this to the Leap 42.1 update, but it was never submitted to
Factory/Tumbleweed AFAICS.
Should be fixed in plasma5-desktop-5.6.1 then, which is on its way to
Tumbleweed already, so we can't really do anything at the moment.

If you want to install 5.6.1 now, use the KDE:Frameworks5 repo.
See https://en.opensuse.org/SDB:KDE_repositories#KDE_Frameworks_5_.26_Plasma_5

Please report back if 5.6.1 fixes the issue, either now (with the KF5 repo) or
when it is part of Tumbleweed.