It's the BIOS that the Xecuter 1 has. It does not support LBA48 and larger cluster allocations. You will be limited to a maximum of 137GB and 16KB clusters.
When Hexen boots, it loads a different BIOS into memory that does have LBA48 support so you see all the space and files you uploaded. But once you reboot, the hard drive access is once again limited to the original LBA28 137GBs accessible by the ancient Xecuter 1 BIOS.
Update: The Xecuter1 BIOS doesn't know how to interpret the data stored at the location of the extended partition 6 that's using LBA48 access and larger cluster allocations. The directory is stored in a foreign language to it Therefore, since it does not recognize the F partition/drive's format, it shows 0 free space or the size of 0.