xvimagesink colour artifacts

[James]

I have 2 programs (it was easier this way)

preview previews a 1080 camera on a qt canvas
record previews the same camera and records it, using matroska mux, although qtmux is the same.

on intel everything works correctly.

on a rockchip 3588 preview works correctly, but record shows areas of green or purple on the preview display.
the recorded video does not have the artifacts
The display looks like *some* shadows are coloured with some 10% of the image covered
preview after record looks normal again

The preview pipeline
       v4l2src name=src ! 
       image/jpeg,framerate=30/1 !
       jpegdec !
       videoconvert !
       queue !
       bla-bla !
       queue ! xvimagesink name=sink sync=false

where bla-bla is textoverlay and clockoverlay stuff

The record pipeline is the same plus mux stuff
       v4l2src name=src ! 
       image/jpeg,framerate=30/1 !
       jpegdec !
       videoconvert !
       queue !
       bla-bla !
       tee name=t
       t. ! queue ! xvimagesink name=sink sync=false
       t. !  queue !
        x264enc speed-preset=ultrafast tune=zerolatency byte-stream=true bitrate=4000 !
        mux. pulsesrc name=pulse ! 
        queue ! 
        audioconvert !
        audioresample ! audio/x-raw, rate=48000 !
        queue ! 
        mux. matroskamux name=mux !
        filesink name=file

Has anyone seen and solved such bizare behavior, or got any ideas
Thanks
James