I have a Lexar 32gb Professional 1000x Uhs-ii SDHC for use with a Canon 5D MkIII to record JPEG files, other slot has CF card in it for recording RAWs.
Trouble is that on my imac the internal SD card reader cannot "see" the JPEGS.
If I format the SD card in my Canon 750D and shoot JPEGs the internal card reader on the imac can see them.
Canon 5D MkIII doesn't support UHS II so it isn't using the extra pins found on this Lexar card.
Just doen't make sense.
Have tried another 5D MkIII so it isn't the camera, and both 5D MkIIIs JPEGs can be "seen" on a Windows computer and also via a USB card reader on the imac.