Dell 7480 and TB16 dock

Hi guys,

Apologies if this has been posted elsewhere (though I haven't been able to find anything). I'm testing a TB16 dock for use with the Latitude 7480 but cannot get it to work with the monitors. it is supplying power to the laptop, but nothing else plugged into it is recognised. I have updated all the available drivers for the 7480 and the BIOS is updated to 1.2.9.  The BIOS was updated first.

When I attempt to install the  Thunderbolt 3 Firmware update, I get an error that "No Thunderbolt controller update supported for this platform ID=0x7A0".  

I have installed the available thunderbolt drivers listed here in addition to the Thunderbolt Software 16.2.52.250

I'm running Windows 10 Pro version 1607 Build 14393.953

Short of uninstalling all the drivers and reinstalling in the right order (again), I'm running out of ideas, so any help would be appreciated.

Thanks,

Steve