I finally plugged in my DR650GW 2-CH I had installed about 1.5 yrs ago (I was too busy to deal with troubleshooting the "Please check the SD card" error). I got a 64GB Sony SDXC Class I 70MB/s.
First, I formatted it using the 10-second press of the "WIFI" button. Worked fine for recording, but wouldn't read on my Mac.
So I formatted the microSD volume on my Mac as FAT32, but still "Please check the SD card."
Next, I tried formatting it from the BlackVue Viewer app, it just brought up the Apple Disk Utility. Reformatted, still "Please check the SD card."
SOLUTION: I researched a little on the internet... you need to erase the DISK, not the volume! Use MBR (master boot record) and MS-DOS (FAT32).
HINT: it still says, "Please check the SD card" until you power cycle the DR650GW.
I'm reading on Dashcam Bros they recommend a SLOWER card? And some here recommend these high performance cards. Is this all just a crap shoot, or is there any verifiable research regarding recommended cards? And my product description says "Up to 64GB support." Anyone successfully using 128 or larger cards?