copy/paste not working

[rikona]

Running Ubuntu 16.04. Also use other pgms from KDE - kate, falkon,
konq, etc, which I use a lot, and other misc non-Ubuntu pgms. Have had a
few copy/paste problems in the past - usually in/out of KDE pgms. But
after the last couple of updates I can't do any copy/paste involving
any KDE pgm. Also copy paste from one KDE pgm to another doesn't work,
and even trying to copy text from one place to another within the SAME
kate document doesn't work! It is MUCH worse after updates.

Is there a way to get this to work? It seems as though KDE stores
copy/paste info into some place that no longer responds to any commands.
Is that what is going on? All suggestions for fixing this, or even
explaining it, would be much appreciated. [fixing would be better :-)) ]

Rik