WD15 dock, MacBook, Thunderbolt

@Googe89  and @Spremmier  you're not doing anything wrong, but Googe89 you should find a new IT shop, because they are completely wrong about being able to use Thunderbolt 2 systems with USB-C docking stations.

The WD15 requires a system that has a USB-C connector that supports USB 3.1 Gen 1 or better, DisplayPort Alt Mode, and (if you want to charge your system from the dock) being charged over USB-C via USB Power Delivery.  A Thunderbolt 2 port can carry "raw" DisplayPort traffic when used as a simple Mini-DisplayPort connector, but then you only get display traffic rather than USB traffic.  Or a Thunderbolt 2 connector can carry a Thunderbolt 2 signal, which carry DisplayPort and PCIe simultaneously (USB would be carried over PCIe between the system and dock), but the WD15 doesn't support Thunderbolt.  And even if it did, you still wouldn't be able to charge the system that way.  On top of that, since Mac OS itself doesn't support DisplayPort MST, you can't drive multiple displays via a single USB-C output even on Macs that HAVE native USB-C.  The only way to run more than one display via a single output on a Mac today is with actual Thunderbolt, which can carry two independent GPU interfaces over a Thunderbolt link and assign one to each display.  But a standard USB-C link only gets one GPU interface, which can only be split across multiple displays when the system and OS support DisplayPort MST.

There's no way to get a Thunderbolt 2 system to run like a USB-C system that supports video output.  Even if you got a Dell dock that actually supports Thunderbolt, such as the WD19TB, I don't think you can plug a Thunderbolt 3 peripheral into a Thunderbolt 2 system, although I haven't tried that.

And Googe89 I'm not sure how the Thunderbolt Display you mentioned comes into the picture.  You say you have two Samsung displays plugged into the dock and that that the displays would work via "a Thunderbolt cable which you have plugged in", but you didn't specify what you plugged it into.  Did you run a Thunderbolt cable from your MacBook to the Mini-DisplayPort video output on the dock and just ignore the USB-C cable entirely?  That wouldn't work for ANY system because the Mini-DisplayPort is a simple video output on the WD15, but once again MacBook is not going to work with that WD15 no matter what you do.

Good Morning, 

Yes @jphughan you are correct, after receiving advice form the IT store prior to purchasing the Dell dock that it would work, they have since reneged on that. After I have explained my IT set up to them and followed all advice they gave prior to purchase on how it should be set up, they now say it can't be done. They also seem to be ignoring my request for it to be returned which is comical in my opinion. So a new IT store is definitely on the cards. 

In fairness, It all seemed too easy anyway and I think we all know when it comes to Mac, nothing is ever really easy. 

I hope you find a solution @Spremmier !

My 2020 macbook air (intel, thunderbolt 3 inputs) worked with my WD15 until 1 month ago. After an update (I think from Catalina to Big Sur), the monitors are always blank now. The macbook still recognized the WD15 - the screen resolution changes, the monitor is identified, mouse & keyboard work, but no video. I even tried a factory reset back to Catalina, but it still doesn't work anymore. 

I'm on this same boat. I just got Macbook Air M1 2020. Same situation, mac recognizes the hardware via display settings, but monitor hardware does not display video... Any new updates from anyone? 

@ntimmytommy and @giothinks  The only thing I can think of that might be worth trying is installing the latest firmware, available from the WD15 Downloads page here.  It hasn't been updated in a while, but maybe the update contains a fix for whatever problem condition was triggered by a macOS update or whatever else may have caused the current problem.  The catch is that if memory serves, the WD15 could only have its firmware updated by a Dell system that expressly supported the dock, because dock firmware updates on the WD15 worked like system BIOS updates in that they ran at system boot time.  It's possible that that's changed with newer updates to the WD15 -- it's been a while since I used one -- but if not then you might be stuck unless you can get your hands on a suitable system, which would be pretty much any Latitude, Precision, or XPS system that had a USB-C port, and maybe some Vostro systems.