HP ZBook Thunderbolt 3 Dock plus third display port

[JScheider]

I want to work with 3 external monitors.

Two are connected to the Thunderbolt 3 Dock.

For the third I have a HP USB-C to DP adapter.

It works fine when connected on the zBook itself.

But connected on the Thunderbolt 3 Dock (Thunderbolt 3 port that should be compatible with USB 3.1 Gen2 / DP) nothing happens.

[Huffer]

I actually have a Zbook G3 and the proprietary Thunderbolt dock and in fact am typing this on it. I have a pair of 4K DP monitors. They are connected to the dock. One is directly into the dock DP port and the other is coonected to a 3rd party USB-C to DP adapter. If I try to hook the second 4K monitor into the second DP port directly on the dock it does not come up as 4K but a much lower resolution. My thought is that there is just not enough video bandwidth to drive 3 monitors off one Thunderbolt port. The dock is connected into one Tbolt port so if you connect the adapter to a second Tbolt port you get enough bandwidth to drive 3 monitors. I see the dock also has an old school vga port have you tried it? 

[bubler]

Check http://www8.hp.com/h20195/v2/getpdf.aspx/4AA6-5088ENW.pdf Depending on the resolution on the monitors it should work.

You could experiment with the hybrid graphics setting in BIOS.

Also test change it to no security for the thunderbolt security level in BIOS.

[JScheider]

Hi, the advice with the BIOS was a good one. I switch it to another security level, booted, switched it back and now it works. Strange.

Edit: after a day of work, I came back today and it wouldn't work anymore. Going everyday twice to BIOS is not a good solution.

All monitors are full HD, so the resolution shouldn't be an issue. Now I switched back to DSUB, but to be honest, you really see the difference in quality.

I'm really disappointed in the products.