Since the BIOS is provided by HP, I would suggest you contact them to clarify the issue.
DxDiag is quite likely the most useless program that Microsoft refuses to kill, hasn't been relevant for...I'd say at least a decade. Press Windows Key + R, type msinfo32, and that'll give you a better idea of the basics of your system. For example, mine, as I'm on my Surface Pro 3 currently. If you want more, there's a free little program called Speccy.
This is the BIOS that you updated to: HP Software and Driver Downloads for HP Printers, Laptops, Desktops and More | HP® Customer Support .
Try changing something in the BIOS and see if DxDiag still indicates Default System BIOS. DxDiag could be just saying your BIOS still has its Default settings from the factory, which means it is still in its original Default Settings. If you have changed some settings in BIOS and it still showing "Default System BIOS" than you need to, as previously mentioned, to contact HP Support to find out why.
Or download SPECCY (free program) and see if it says the same thing or shows the actual BIOS installed, as also mentioned previously.