I was experiencing the same issue with the new sharpening model in release 1.3.0, and spent quite a while, finally finding the download link for the previous release 1.2.10 here: Topaz Photo AI v1.2.10.
I strongly recommend to uninstall the current version first. I did NOT do so, ending up with a corrupted version. After completely uninstalling everything (with the caveat, that you obviously don’t need to delete all the *.tz model-files and *.json files in the ‘models’ folder), it works again. (sigh!)
