So, I was shooting yesterday and I was slapped with an error in either my FS5 or in the card it was recording to. I'm curious if anyone has seen this before. After shooting for a couple of hours in 1080P, I noticed my REC indicator was no longer visible. And, there was no STBY indicator either. I also noticed the "A" card slot icon was visible in the top of the LCD and it had an arrow, either going back and forth in the "A" card icon or around in circles in the "A" card icon (hard to recall exactly because I was trouble shooting quickly). After initially losing my mind because I was in the middle of a scene, I noticed my rear tally light was still illuminated, but the blinking light near the card slot was gone. I hit the record button, nothing changed. I tried a different record button, nothing changed. I powered down the camera and a vague frame image remained. I'm not sure if it would have eventually disappeared, because I pulled the battery. After replacing the battery and powering up, I continued shooting... on that card (not the best decision). After the shoot, I noticed the clip was not on the card, but the clip I recorded after powering back up, was there. After the shoot, I ran the camera with a different card on AC power, for about 4 hours. Then today, I ran the camera for another six hours, starting and stopping periodically to try to replicate the problem, but the camera was perfect. If anyone has had a similar experience, I'd love to hear about it. If anyone can provide insight or possible ideas as to what happened, I'd greatly appreciate it. Thanks everyone!

Not had this. As an aside, I ALWAYS simultaneously record to both card slots ...always build in as much safety contingency as you can! (but don't forget any slomo will ONLY appear on the card in Slot A).

So what make and exact specification of SDXC cards were you using in your FS5?

I would definitely not use that specific card in your FS5 again - high spec SDXC cards, even when bought from a cast iron legitimate source (to reduce the risk of buying a counterfeit) are so cheap now I wouldn't risk using that specific card again.