Here's what I'm doing:
1. Open Google now and search
2. Highlight text in the results with a long press and some tap and dragging
3. Tap the copy icon in the clipboard tab at the top.
4. Receive the toast "the clipboard history was cleared"
And indeed, what I just copied will not be I'm the clipboard. Any way to fight this weird Google Now behavior?
Problem solved! The culprit was the xposed module " Secure Samsung Clipboard"