Try SMC / PRAM Reset?
With references to APFS and fusion, it seems like it might be trying to mount a visible filesystem.
If the intention is OS install, try erasing the disk from recovery mode and formatting as something ‘boring’ like ExFAT
Try SMC / PRAM Reset?
With references to APFS and fusion, it seems like it might be trying to mount a visible filesystem.
If the intention is OS install, try erasing the disk from recovery mode and formatting as something ‘boring’ like ExFAT