That all means nothing. Have you actually tested those cards to see how they were? If they are faulty in any way you are going to get upset once data start corrupting.The card works in my phone. It's a Samsung sd card. I've already done all of those test. I'm just going to get a regular 128 gb micro sd card from Sandisk. The Samsung one must not be compatible in some way. I've transferred from a 32 gb to a 64 gb 4 months without any issue. Both cards were Sandisk.