Grab Stills not working in colour tab

Hi. In 16 I could grab a still in the colour tab by right clicking on the image. This would put a thumbnail of that still to the left of the playback window. I could then right click on that thumbnail and export the image to a folder of my choosing. 17 will not do this. A right click on the video will show the drop down list of options, including grab still, but nothing happens.

I can't duplicate this in Studio 17b7 for Windows. Both Grab Still and Export work fine.