[Mike]

The card was formatted exactly as the now two working small capacity cards were. one card is a Class 4 PNY 8GB, the other is a Sandisk Ultra 32GB Class 10. All were formatted Fat32 on a Macintosh, then reformatted in the unit using the iPhone App. More oddly the Large Samsung 256GB even worked to update firmware, but the K3 doesn’t want to write to it.

On the small capacity cards the file system is laid out correctly and FAT32 maximum length MP4 videos record fine.

On the Samsung PRO Endurance the file structure builds, but a single pair of 0KB MP4 files are saved, and the camera icon flashes.

Doing some research it appears the Pro Endurance has an odd write spec to it in order to ensure data which makes it act unusual for a Class 10 U3 card, are you certain the Samsung PRO Endurance 256GB is a Supported card?

Can you give me either the FULL spec requirements, and a list of VERIFIED tested cards in the 256 and 128 GB size that are KNOWN to work with the K3? Because it seems to work fine aside from with this particular model of 256GB card.