Precision 5520 - Three External Monitor Support?

I have a Precision 5520 through work that I'm trying to connect to my three u2720q 4K monitors

While connected to these external monitors I do not need the laptop LCD. I have tested this configuration after disabling the LCD and am still having the issues described below. 

I purchased a thunderbolt 3 to DP adapter from Plugable to allow me to connect a third monitor to the laptop. With this, two monitors are connected to DP via the adapter and one his connected via HDMI directly to the laptop. 

The problem is only two of these will ever work at one time.

- Connecting the two DP monitors first followed by the HDMI results in the two DP monitors working but not the HDMI

- Connecting the HDMI monitor first followed one of the DP monitors (or one of the DP monitors followed by the HDMI monitor) results in the HDMI and first DP monitors to work but the second DP monitor is not detected

The issue therefore doesn't seem to be with the adapter, but with how the system is configured. 

When I look in Device Manager both monitors that are working are located on the Intel Graphics, not the Nvidia GPU. 

I unfortunately don't have the ability to access the bios since this is a work machine. But in theory this configuration should work correct? Reading through other posts here on the Precision 5520 imply that three external monitors should be supported. 

I have updated both the Intel and Nvidia drivers. Unfortunately, again, I can't do much with the BIOS. Is there any other configuration settings I might be able to try to get this working?