PDFs to KFX on Kindle Scribe issue

Ok, I have this workflow to convert PDFs to KFX files on the Kindle Scribe.

1. Convert PDF to Black and White using Ghostscript.
2. Make a print-replica kpf file using Kindle Create 1.85.0.0
3. Use Calibre and Kindle Previewer 3.79.0 with the kfx output plugin to create a kfx from the kpf
4. Add to calibre, add metadata and sync to Kindle Scribe.

The problem I have with this process is Kindle Create, I think. Only some links in the resulting kfx file work. And I also cannot highlight text on some pages, while other pages work fine. And searching on the book will only find results on the pages that I can highlight text on.

So, I went another route.

I uploaded the PDF using the Send to Kindle website and then downloaded it my hard drive using Calibre. I then deleted the book from my cloud library, threw it in calibre, updated the metadata, and synced it to the Scribe.

On the Scribe, everything works. I can highlight text on any page of the book. All the hyperlinks work. The book has the proper title. The only thing that doesn't work is the cover. The cover has a generic pdf icon.

I've plugging the Kindle back in to force Calibre to refresh the cover art, and I've tried the ASIN trick. Neither one give me genuine cover art.

Is there some trick I can do to force cover art?