Yes — based on the community responses, the Nikon D300 itself does not reliably support 64GB CompactFlash cards. The issue is tied to the camera’s support for larger-capacity cards and exFAT-era media, not just the card needing a normal reformat. Formatting on a PC or in-camera usually won’t fix it if the body is incompatible.

Some users have reported a workaround by creating a new active folder in the Shooting Menu and then formatting the card, but the more consistent answer is that 64GB CF cards are not supported on the D300. The D300s is a different model and may support 64GB cards with firmware updates, but that does not apply to the D300.

Practical fix: use a smaller CF card that is known to be compatible with the D300, and format it in-camera before use.