Looks like it's a windows specific issue for the plugin. I was using prophoto for the image, even though I'd been doing web work today and had the default working space as sRGB. I found a similar issue when testing DxO filmpack a few years ago, which the developers had missed :-) This is now something I always look for when testing new software
Have you tried the Topaz forums/support? I'd have thought such an issue would have been spotted if common? I can't offer any other ideas, since we're entirely Mac based.