Thanks to the new "smart" TV that can't handle exFAT, I have to format a 64GB Samsung USB flash drive as NTFS. Seeing it going at 9MB/s, I got "greedy", and started a second file copy operation to the ...
The error Unrecognized partition found, index 1 disk layout validation failed occurs while converting MBR to GPT. This article lists the reasons and fixes for this error.