How big are your drive's sectors?

From the days of old, hard drive sectors have been 512 bytes. That created problems, however, when drives started getting bigger than 2 terabytes because MBR-partitioned disks only set aside 32 bits to indicate how big a partition is. Therefore, no partition could be bigger than 2^32 sectors * 512 bytes/sector = 2 TiB. GPT has effectively superseded MBR and solves that problem, but there are other reasons (efficient error detection, for instance) to want larger sectors. Some drives available now are in the Advanced Format, with sectors 4,096 bytes long. Interestingly, though, some of those drives present themselves to the OS as classic 512-byte sector disks for compatibility.

You can see your drive's real and presented sector sizes on Windows by running this command:

fsutil fsinfo sectorinfo c:

(Replace C with your drive's letter if necessary.) In the output will be a LogicalBytesPerSector value (what your OS sees) and a PhysicalBytesPerSectorForAtomicity value (the real deal), among other data.