I had an issue where I removed a drive in my ZFS array and replaced it with a new drive which the OS gave the same device name (/dev/sdd). I had a hard time getting zfs to replace the drive until I discovered the -g flag for zpool status (thanks to this stackexchange post.)
That did the trick! Simply running zpool status -g showed the GUIDs of each device, which I could then use to properly use zpool replace on:
sudo zpool replace Poolname 12922644002107879117 /dev/sddSuccess!