The SanDisk Extreme PRO 512GB card is on the supported list, but my R5 refused to recognise it, even after formatting in MacOSX and Linux. I raised a support call - who suggested that I made a 'long format' on Mac OSX.

However, since Big Sur (and perhaps before), the longer option for Solid state devices have been removed.

So I used the following to write zeros at every position on the card:

sudo dd if=/dev/zero of=/dev/disk3
dd: /dev/disk3: end of device
1000215217+0 records in
1000215216+0 records out
512110190592 bytes transferred in 20238.107872 secs (25304252 bytes/sec)

As you can see this took nearly six hours! It worked, the card is recognised by the camera and I can now use video with the R5.

If you need to use this yourself ... you need to be ABSOLUTELY sure that the /of=your_card_disk_device is correct - otherwise you run the risk of unrecoverable wiping of one of your disks.

You may need to unmount the disk first, I used:

sudo diskutil unmount /dev/disk3s1 <- this is the formatted partition on the disk.
- Volume R5EXFAT on disk3s1 unmounted