XPS 9360 with Ultrawide display

@DrNinjamonkey  Initially I thought that the display might not accept its native resolution over HDMI, since 2560x1440 at 60 Hz is the most you'd get if you were dealing with a display that only had an HDMI 1.4 input rather than an HDMI 2.0 input, and there are some displays on the market that only accept their native resolution over DisplayPort because the newest HDMI revision at the time they were engineered didn't support the display's resolution (DisplayPort has always been ahead of HDMI at any given time in terms of resolution).  But the documentation does mention HDMI 2.0, and the cable specifically claims HDMI 2.0.  I remember an issue reported on the Intel forums a while ago where a driver released in January 2020 broke support for 5120x1440 and limited those displays to some lower resolution, but you're not going that high.

So my only immediate suggestion if you'd be open to it would be to get a USB-C to DisplayPort cable instead. The reason is that USB-C ports use DisplayPort for video output anyway, so a USB-C to HDMI adapter/cable has to incorporate an active signal converter chip to switch that signal to HDMI, which is just one more thing to pay for and potentially cause problems, as may be the case here. A USB-C to DisplayPort cable can just pass through the signal that the laptop is sending. (USB-C to HDMI adapter/cables also tend to be more expensive all else being equal because manufacturers are required to pay the HDMI licensing organization a royalty for ever HDMI connector they install on a product, whereas DisplayPort is royalty-free.)

I actually just recently helped someone here who had a USB-C to HDMI adapter that wasn't working at all with some Latitude system they had even though it did work with another laptop. After some troubleshooting, I basically said, "This is either a hardware problem with your Latitude that would require a motherboard replacement [he didn't have another way to test USB-C video output from his system] or some bizarre interoperability problem between your specific system and that specific adapter that shouldn't exist but sometimes crops up in the tech world. But since the former would be a huge ordeal to address, you might want to just try a different brand of USB-C to HDMI adapter/cable." He tried another adapter and the next one worked fine with both of his source devices.  So that might be what's going on here.  But again, if you're open to trying another cable, I'd just go USB-C to DP to keep it simpler.