Comment # 9 on bug 953954 from Wolfgang Bauer

(In reply to Jaroslav Kamen�k from comment #8)
> It does not help:( Blank spaces disappeare, when I hide App. state category,
> but are still blank after switching it on. Tried few combos of categories,
> hide all etc, same.

Well, then you seem to face a different problem.
This reliably works here to make the missing icons appear.

So this only happens with Opera, Pidgin, and Skype?
Maybe switching to a different icon theme might help?

Of those 3 programs I only have Opera 12.16 installed here. And the icon
displays fine.

It might be a problem in xembed-sni-proxy though (used to display old-style
XEmbed icons in Plasma5), that is fixed in a newer version.
Can you please try to install the package from KDE:Frameworks5?
To do that run this e.g.:
sudo rpm -Uvh
http://download.opensuse.org/repositories/KDE:/Frameworks5/openSUSE_Leap_42.1/x86_64/xembed-sni-proxy-0.0.1git~20151029~11e8648-6.1.x86_64.rpm

For Skype you could also install sni-qt-32bit to make it use the new-style SNI
instead instead of the old XEmbed, for Pidgin try libappindicator1.
But please try to newer xembed-sni-proxy first to see whether this fixes it (so
that we know whether we should release that as update...)