Help! Trying to connect Dell Latitude 7490 laptop to LG Ultrafine 4k monitor

Hmm well the LG Ultrafine 4k monitor works great with my Macbook pro. I connect the monitor's thunderbolt cable from back of monitor straight into the Mac.  When I do the same exact thing with my Dell 7490 the monitor doesn't show any video but I hear audio.  Not using any usbc/hdmi adapters - just using monitor's thunderbolt cable from monitor straight to Dell 7490. 

When I go into display settings for the Dell, it lets me choose the LG monitor as display 2 but then says it's not active.  "Display 2: connected to Intel UHD Graphics 620. Display 2: isn't active"

Totally stumped.. it seems like it should work.. maybe the Dell 7490 can't handle the LG Ultrafine 4k monitor graphics or not compatible somehow?

Thanks! Pam

@PaEl  That should work fine given that the 7490 came standard with Thunderbolt and its GPU supports 4K. Have you updated your BIOS, Thunderbolt controller firmware, and GPU drivers? What about the firmware on the display if applicable? Have you tested whether the USB-C to HDMI adapter works with another display/TV, just to see if this might be an issue with the system’s USB-C/TB3 port?

@PaEl  I mentioned USB-C to HDMI because your first post said “I've tried 2 USB/Thunderbolt to HDMI adapters”, so I was just wondering if you had validated that those worked properly elsewhere. But having read that post again, you’re using those adapters backwards. You can’t use a USB-C to HDMI adapter to connect an HDMI output to a USB-C input. You can only use it to connect a video-capable USB-C output to an HDMI input. But if you want to run that test to see if you can connect your laptop’s USB-C output to an HDMI input on a TV, that would at least verify that video output from your system’s USB-C port works.

And did you update your BIOS, Thunderbolt controller firmware, GPU drivers, and display firmware as I suggested?

Hi there! Yes I'm realizing that I can't use those type of adapters because I'm using them in the wrong way - so am returning them.  

It is a work PC  computer with admin access to get into the actual computer system and check updates on things.. so I have reached out to my work IT to see if they can help with checking the PC on that.

Guessing it's just not as easy as with my Macbook pro to plug and play with this LG Ultrafine 4k monitor. Thanks!

@PaEl  It should be plug and play, but since it’s not, I suggested connecting to a TV using that adapter. If you haven’t returned the adapters yet, I’d still suggest doing that, even if you end up having to contact IT to get help with updates anyway. It’s quick after all.

ok yep I took your advice! I did hook up my usbc/thunderbolt to hdmi adapter. Going from laptop usbc/thunderbolt to a tv hdmi and it works. I guess it just doesn't work the other way around.. using the usbc/thunderbolt from monitor into hdmi into laptop. Wonder if there are multi directional adapters? 

thanks for your help!

I have recently come across this same issue with the sound and no display when connecting up to this monitor. To fix it I simply changed the display settings > multiple setting and extend displays. :)