I did a bit of research and ...
MS-DOS partition table (the "MBR" of yours) has indeed space for four entries, of which at most one can be "extended partition" while the others are "primary".
The extended partition is a head of a chained list of logical drives, and serves as method to have more than four partitions on the module.
However, in your case we do find an another feature of the MS-DOS partition table. The partitions are described with "start" and "end" LBA indices. 32 bit indices, I guess, which means that an LBA beyond about 2TB cannot be addressed.
In short: "MBR"
cannot address more than 2 TB. Use GPT partition table instead.