fish1050
Headphoneus Supremus
I was using the card in a USB 3.0 reader, not in the Sony. However, I tried formatting it with the SD Association tool and now I'm able to write data to it again. I hadn't tried formatting it earlier today though I had formatted it using the Windows 10 formatter since getting it. I'm again trying to copy a huge chunk of data to the card now and will report back the results.
Presuming the data copy fails again the card is going back to B&H since they'll cover the return shipping and I've only had it a few days. Dealing with Lexar means I will have to pay to ship it. You appear to be correct on the warranty though. Lifetime, the reader has the 1 year warranty. I was going off the warranty information listed on the B&H product page.
Edit: Happened again. This time slightly sooner at 60.4GB into the copy.
You mentioned two Lexar cards failed, did you get them at the same time? If not the other failed card should be covered under the Lexar lifetime warranty. Are you planning to try and return that one as well?