which SD card is it exactly?
Was the Sd card formatted in the phone?
Do you have a laptop or card reader for your pc that you can test the card with?
Its a micro sdhc samsung 64gb fresh out the box. when i got it i didnt try any formats i just put it in the s5 and went for it, then same problems happened so i formatted it in the s5 still having issues. the memory card works fine in the laptop but when it comes to using it in the s5 saving high res vids or pics they always crash, even if i transfer them from phone storage to sd storage. I looked up if the s5 can take 64gb sd card and it does. Could be my phone thats acting up but smaller gb micro sd cards work without a problem.....