Bizarre, worked for a collection of tags, went further t try to do series as well and it stopped working - preview now shows zero files being put into collections, but the collections are being made, just empty.
reinstalled plugins, no joy.
uninstalled and reinstalled calibre, working now, i'm using series this time. Doesn't sort by the order of the series at all. Bit flaky overlal this experience.
EDIT: When I go into customise again, and do the preview, the colections are being crested again, but again WITHOUT any content, all zeroes. Thoughts?
EDIT 2: Reinstall Calibre again, all working, don't even have to reinstall plugins.
Yet, when I need t do another Preview or Create, ZERO books in collections again.
Lastly: wasted half a day on this, argh!