Can anyone help with 'Slow SD Card' message and video recording stopping after 20 seconds. Card installed is new genuine Samsung Evo+ SDXC 64Gb Class 10 UHS-1. I have tested the speed and get circa Read 17.1MB/s, Write 10.1 MB/s.
Thanks guys. Just back from the shop where as if by coincidence I purchased a Scandisk Extreme A1 UHS-3 V30. Yes a bit of overkill for 1080p camera but it is working nicely now. Having done some Googling it seems I'm not the first to have issues with the Samsung 64GB UHS-1 (as listed on recommended SD cards list). I'll steer clear of that brand from now on.
How many Slow SD Card messages did you receive? When I first installed my new Samsung card the Spark was reading similar message. I selected Format under the quick menu and reformatted the card. The message hasn't happened again since.