Sounds familiar to me, I had similar issues. If your unit wasn’t brand-new, I would try out this (reasonably easy to-do) fix. Note, this tutorial talks about ‘bleeding’ but this fix also addresses the defective CF assigns, aka the CF not doing anything at all. Took me 5 minutes and now it’s working fine again:
But in your case, I would simply return it (and of course tell the seller why, so they can service it).