X4 SD Card Size and Format

Insta360 X4 and I have a SanDisk Extreme Pro 512GB (new) that is A2 V30 formatted in exFAT. The camera will not turn on. The SD card works in my PC, as it can be written to and read from. However, my camera does work with a 256GB SanDisk Extreme A2 V30. Any insights into why this might be happening?"