Broken copy-paste after 49.../50 days

After 49 days and a bit (lets say 50 days) copy and paste within qt-powered programs is broken. I can copy from e.g. firefox and past it in konsole or telepathy. But whatever I copy from such programs is not copied.
Restarting the programs helps.

At first I reported it inclusive a similar issue to KDE:
https://bugs.kde.org/show_bug.cgi?id=381823

Which lead to (which is fixed but was said that this should be reported here):
https://bugs.kde.org/show_bug.cgi?id=377901#c18

Klipper also has no new entry since. Not even those copied from non-qt-programs.