XPS 13 9300, BIOS 1.0.10, USB Type-C to DP adapters no longer work

So I tested it and got 4k at 60Hz without problems with a FullHD XPS13 9300 with Intel Iris Pro.
I really don't think that should be a problem.
I worked with a UNI USB-C-to-DP without any problems.
Even with the tested Dell adapters everything worked.
look at the screenshot and explain yourself.

BIOS @ 1.1.0
Firmware in Windows @ 1.0.11
Latest GFX Driver by Intel
Latest Driver by Dell4K @ 60Hz

How about USB-C to HDMI with or without a Thunderbolt 3 dock between?

If you're running Ubuntu and want to check your Thunderbolt firmware version before and after the upcoming BIOS update, run this command:

sudo fwupdmgr get-devices

On my machine on BIOS 1.1.0, the Thunderbolt controllers are reporting version 80.00.

The BIOS is 1.1.0
My thunderbolt firmware is 80.0
My test was without a DockingStation.
USB-C-DP adapter: https://www.amazon.de/uni-DisplayPort-Kabel-DisplayPort-Kabel-Space/dp/B081ZZSV2S
USB-C-HDMI adapter: https://www.dell.com/de-de/shop/dell-adapter-usb-c-zu-hdmi/apd/470-abmz/netzwerkl%C3%B6sungen
If further tests are needed with DockingStation, I would have to offer a WD19TB.

I updated yesterday from BIOS 1.0.11 to 1.1.0. The problem is still there, zero improvement, and the device manager strangely still says 1.0.11.

I received a call from German DELL support today confirming 4 September 2020 as the scheduled launch date for an updated BIOS that fixes the problem. We'll see.

What a disaster for DELL. If they blow it again, they can take the laptop back and count me out as a customer after 8 years.

Agreed - two problems:

- USB C to DP and HDMI not working

- Poor customer communications

Next time, I will buy an ALDI PC. Their service is definitively better, and the PC costs a fraction.

My XPS 13 9300 just won't connect to my lg 27UD59 4k monitor via a Choetech USB-C to DP port cable. The cable works fine with a Mac book Pro going to the same monitor. If I connect my Dell to a USB-C hub (Dell DA300) and then use a DP to DP cable between the hub and cable  then it works fine as well. 

I've spent nearly 2 weeks with Dell support via WhatsApp back and forth every day. Bios (1.1.0) and drivers all up to date. 

I even mentioned this thread in the discussion and asked whether a BIOS fix was a reality. To be honest the support from Dell was a joke. I finally ended up calling support in the UK and got through to someone who seemed to know what they were doing. After a brief (60min) call during which support took over my laptop and having told them about this thread they did state the a BIOS fix was coming in 1.2.0. They wouldn't commit to a date (understandably in my opinion) but said within the next month. 

Fingers crossed. Not sure why its taken 2 weeks on WhatsApp and a1hr support call before they finally admitted that a BIOS fix was coming. 

And now we have the answer: nope.

Why thank you Dell,

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Changelog in BIOS 1.2.0: Fixed the issue where Dell logo flickers towards the bottom of the display during boot.

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I think I can now forget about the 3rd party USB-C monitor not working as well as removal of Fn+Arrow keys to work as Home/End buttons. What a major version bios update.

I've just updated my bios to 1.2.0 version, my third party adapter (Mobility-Lab-MAC8010) is now working.

Thanks to everybody involved in this thread and the bios team!

No change for me, still broken.

I have already change the Screen/webcam/Microphone.. the next monday I change motherboard+fan...

Worst PC for me...

Updated this morning, confirm my 3rd party USB-C to HDMI adapter is working with my monitor.  Will check my TV later.

Yep. Same here. Loaded  BIOS 1.2.0 which released today [4th September] and it fixed my issue. When I plug my  XPS 13 (9300) into my  LG 4k monitor (27UD59) via a Choetech USB-C to DP cable the external monitor works. Before it just didn't. Have tried unplugging and hot plugging usbc cable several times and the monitor is recognised every time and running at 60hz refresh rate. Cold boots also work perfectly. As they should have done all along. 

Well Dell you got there eventually so thank you for that. Maybe next time be more honest and open about things. But thanks again and thanks to everyone on here as well, particularly those who helped get us site info about what was going on. 

Cheers

Still seeing the same issue on bios 1.2.0.

My usbc-HDMI has been working ok if connected directly to the thunderbolt port. The issue I have is with the Caldigit ts3 plus thunderbolt dock.

I have two monitors, the one connected to the dock via DP works perfectly. The one connected to the dock via USB-C-HDMI occasionally works, but the resolution can't be set correctly.

I have contacted the support and they said the engineering team aware of the issue and plan to address it on another bios release in November 2020.

I'm going to return my 9300 as my 30-day window ends soon. I was expected this should've been fully fixed on bios 1.2.0 but it doesn't, who knows what might happen in November...