Something to be aware of is the possibility of counterfeit/fake SD cards which may be sub-performing lookalikes of the real thing. Buy from a reputable well known seller. I would probably avoid eBay altogether and if Amazon, buy from Amazon as the seller and not a 3rd party. A counterfeit may not be the problem you are having, but something to consider depending where you bought it from.
https://www.amazon.ca/gp/customer-reviews/R1OIIJASRFJGFH?ASIN=B00PLENZPC