Pattern to record: Free space is implausible or files overlap and report read errors.

Identify the storage layer

Confirm that the external volume is actually exFAT and record which computer or device last wrote to it. Compare the cable and enclosure as well as the volume; a shared drive may encounter different host policies on Windows and macOS. One possible explanation is that used and free space records no longer agree with actual file extents.

Protect data before repair

Cancel format prompts until required files are secured. Continuing normal writes can allocate blocks still belonging to files.

Evidence to check on the protected copy

1. Test the device and connection read-only before deciding whether the issue is media or file-system damage.
2. Validate allocation structures against file records on a clone.

Recovery and verification

If the checks support this cause, rebuild the allocation metadata or recover files to a clean volume. Verification should cover cross-platform mounting, large file transfer, safe removal and backup.

For an assessment of your external storage device, contact AEPC in Burswood or call 027 908 8880. Provide the model and the conditions that reproduce this problem. Workshop visits are by appointment.