Mike S wrote:

I think the card is junk and the EBAY seller isn't responding, I'll
chalk it up to learning not to bottom-feed.

You could start a return process at eBay whether the seller agrees or
not. I don't remember how long eBay requires you try to contact the
seller before opening a case with eBay. If eBay cannot get the seller
to respond, you should be cover by their Buyer Guarantee which means
they'll pay you back. I've done this with eBay a couple times (out of
so many transactions that it hasn't soured me at all on buying at eBay
but I do a lot of investigation first). One time eBay refunded me
without me even asking them. Turns out some ahole had sliced up an MS
Office 2003 volume license the result of which is that buyers eventually
couldn't revalidate their license. They refunded in about a month
perhaps due to complaints from others. It was 2 years before I realized
why they refunded when I could get Ofc2003 revalidated after a fresh
install of the OS.

Thanks for the recommendations, I bought a Samsung 64GB 100MB/s (U3)
MicroSDXC EVO Select, fingers crossed. Thanks!

Come back and tell us the results, especially with a comparison of
CrystalDiskMark with the old and new SD cards.