Hi,
I had issues formatting a SanDisk 64GB SD card, using DCS-8330LH. I solved the problem by doing the following:
1. Disabled all video streams (I use Synology), and disable Schedules and Automations in the Mydlink app.
2. I formatted the card to ExFat on Windows 10. Notice I could not get it to work when formatting it on Mac, using Fat32.
3. Format the card again via the Mydlink app