Feature Request

I haven't been able to find a way to regenerate PDF thumbnails. Reason I'm trying to is there must have been a bug in WordPress 5 that stopped this from working. It seems to be working now, but I have 50 or so pdfs that I need to regenerate thumbnails for. I tried WP-CLI command "wp media regenerate IMAGEID" and for PDFs it returns the error "No images found". While it works for regular images, it would be nice for this to work for PDFs as well.

Thanks,
Matt