I get an intermittent issue with my chocolate bars. Every so often I’ll turn out some which have a patch of bloom-like discolouration and can stick to the moulds. I’ve tried to find a pattern to try and understand the conditions under which this happens, but it’s a problem which might affect 2 out of the 3 bars in the mould, or one mould in a batch of 10, for example. It’s something which needs investigating, but that needs time. For now, all I can do is note down whenever it happens along with temperature, humidity, timings and so-on to try and discover a pattern. My gut feeling is that the chocolate has cooled too slowly.