"Invalid partition layout" is not a filesystem problem, the disk lost/damaged some part of the MBR, looks like it mostly happens with WD disks, so possibly a firmware problem.
To fix you can rebuild the the disk, assuming parity is valid, you just unassign it, start the array, Unraid will recreate the partition correctly and emulated the disk, if all looks good you can then rebuild on top, alternatively you could mount the disk outside the array and copy the data back to it.