The workflow I'm using at the moment is to open a raw file, apply AI Clear, turn HD Preview ON, and then complete the image with various adjustments. That works pretty well, except there is some weird anomaly where the preview "blacks out" for a second with some adjustments, then returns. Very strange indeed; probably related to the bug you've mentioned. Another workflow I was playing around with, yesterday, is to turn HD Preview ON only for those adjustments where I think it critical to properly see the actual result; such as Precision Contrast and Precision Detail. I don't think adjustments such as the Tone Curve, HSL, etc, require HD Preview. But, I will continue to experiment. Hopefully, Topaz will figure out the bug and/or anomaly I've mentioned because it is a bit startling during an edit session.