Set KWin to use EGL via KDE System Settings.
With Version 2.99.917-6.20150211.fc22 everything works fine, with 2.99.917-15.20150729.fc22 several Plasma widgets (most notably the digital clock) stop updating after a minute or so.
Fedora 22 changed to end-of-life (EOL) status on 2016-07-19. Fedora 22 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.
If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
are unable to reopen this bug, please file a new report against the
current release. If you experience problems, please add a comment to this
Thank you for reporting this bug and we are sorry it could not be fixed.