2018 MacBook Pro Target Display Mode Not Working

hey guys, just want to confirm that I used Belkin Thunderbolt 2 Express F4U085TT to connect my MacBook Pro 2018 with an iMac 2013. The iMac can be used as a target display. No flickering, no dark display. It just worked flawlessly.

Basically, you need a Thunderbolt 3 to Thunderbolt 2 adapter and the Thunderbolt 2 cable that comes with the dock to connect your MacBook Pro to the dock. then need another thunderbolt 2 cables to connect the dock to the iMac. I know it sounds stupid but it works.

SOLVED with public 10.14.1 update on both machines.

With the launch today of macOS 10.14.1, I updated just the iMac. No dice.

I then updated the Macbook Pro, and lo and behold, with both machines in 10.14.1, Target Display Mode now works out of every port on my MBP! No more wonky screen!

I do have to be logged into a user on the iMac (guest works too), otherwise I just get a black screen. Not sure if that is how it previously worked.

You need Mojave 10.14.1 Beta 3 - that's when the fix was implemented. The iMac doesn't need to be updated, mine is still on High Sierra and it now works with just the MPB on the latest Mojave beta

Another workaround! Just for fun, I tried daisy chaining from the Apple Thunderbolt 3 to 2 Adaptor through my Thunderbolt 2 RAID (Rockstor-4disk) up to the iMac Thunderbolt input. Thunderbolt Display Mode worked when I entered command F2! So you don't really need an expensive Thunderbolt All in one adapter (I'm using the CalDigit TB3+) to daisy chain through as it looks like you can daisy chain through anything and get it working. It's as if the daisy chain may slow or filter the "glitch" that is causing the problem. Someone mentioned it could be the new 2018 MacBook Pros Thunderbolt 3 controller may be too fast and in essence daisy chaining slows it down. I discovered this because I wanted to use my Thunderbolt 2 RAID AND my iMac in Target Display Mode at the same time (without having to buy another Thunderbolt 3 to 2 adapter) and found it actually worked. I'm using a late 2011 27" iMac running Mac OS X 10.13.6. One caveat is that you have to turn off the iMac and restart the MacBook Pro to get it to recognize the Thunderbolt 2 RAID before engaging Target Display Mode after the iMac restart. Another problem with this set up is that the iMac mounts the RAID when you disengage Target Display Mode. Hope this info helps someone.

I've got the same issues & escalated @apple as well.

One workaround: If I connect MBP and iMac through a 1st Gen Belkin Thunderbolt dock, Target Display Mode works flawlessly.

Apple Support is trying to figure out what the dock is doing differently to make it work...

Cheers, c

As I posted previously I have the same issue with a new 2018 13" MBP and a Mid-2011 iMac (which worked perfectly with my mid-2015 15" MBP. I could not wait any longer for Apple to fix so I went ahead as others have suggested and purchased a hub. An unfortunately expensive solution but A SOLUTION. I can confirm as others have that it does indeed work. I purchased the CalDigit TS3 Plus+ plugged in using the Apple TB3 to TB2 adapter and I'm up and running. It stung a little to have to shell out more money on top of the already large expense of a new laptop but the bonus upside is that I now have ports for any peripherals that don't have TB3.

SWEET JESUS THEY ACTUALLY FIXED IT!! Update to Mojave 10.14.1 Beta 3 if you can to experience a sigh of relief. Side note I have not updated my iMac to Mojave yet and its still works so it looks like you only have to update the MacBook

Hi, after I downloaded 10.14.1 Beta yesterday I was able to connect only to one of the 2 iMacs that I use with my MBP 2018 through the bottom left USB C to Thunderbolt 2. However this morning when I came to my office and connected again to both iMacs through thunderbolts, the one connected to the bottom left USB C and the other to the top left both connected with Command+f2 without hesitation apart of having to tap cmd+f2 twice in sequence on each iMacs keyboard. It seems the problem has been solved so I agree now that when downloading 10.14.1 Beta the problem seems to be solved! Thanks for coming back to me.

It works with just the install on the MBP 10.14.1, no need to update the iMac, tested and currently working perfectly on 2018 MBP with apple adapter from USBC to Thunderbolt 2 connector and cable to iMac Late 2013, confirmed the 10.14.1 update fixed it to how we had it running before with TB2 to TB2 on the old 2014 MBP

Solved on 2018 MBP 13" with TouchBar to mid-2011 iMac 27" and late-2013 iMac 21.5". Using the Apple Thunderbolt cable, my iMacs easily switch Target Display Modes with each other .. just beautiful. But even with the Apple USB-C to Thunderbolt adapter and the same TB-to-TB cable, from 2018 MBP to 2013 iMac worked only sometimes and often did the flickering deal. To the 2011 iMac, all I got was a black screen on the iMac. Finally I remembered my company had given me a Belkin dock which I don't use since the MBP can drive 3 external displays by itself. Using the dock, I connected my MBP to the dock with a USB-C to USB-C cable. Then plugged in the USB-C to TB adapter to the second USB-C port on the dock. Plugged in the TB to TB cable to the adapter. Now both iMacs go into TDM easily and stay connected with no flicker at all. MBP runs High Sierra (I cannot update to Mojave yet, since it breaks some company proprietary apps), 2011 27" iMac runs High Sierra and 2013 iMac runs Mojave.

This is the dock

https://www.bestbuy.com/site/belkin-thunderbolt-3-express-dock-hd-silver/5947892.p?skuId=5947892&ref=212&loc=1&extStoreId=1501&ref=212&loc=1&gclsrc=aw.ds&&gclid=EAIaIQobChMI9ueqgJC94AIVWR-tBh0CGwL1EAQYASABEgK_i_D_BwE

I had to upgrade my 2018 15" MBP to Mojave for the iMac TDM to work.

Thanks to your post, I now have my 2018 MacBook Pro working with Target Display Mode through a CalDigit TS3+! I had the exact same problem as everyone else (flickering and shut off using Target Display Mode to iMac through the Thunderbolt 3 probs on the MBP) but it is working solidly now with 2 monitors connected through a CalDigit TS3+. I have a Dell 30" monitor using the DVI port of the CalDigit, The iMac is connected to the Thunderbolt 3 port on the CalDigit using an Apple Thunderbolt 3 to 2 adapter and Target Display Mode is engaged. I wanted TDM to work via a separate MBP connection because I need the Apple adapter to connect to my Thunderbolt 2 RAID. At least for now I have a dual monitor setup.

It's this dock: https://www.macworld.com/article/2037026/review-belkins-thunderbolt-express-dock -lets-you-get-plugged-in-easily.html

The USB-C / TB3 to TB-Adapter works fine for connecting the 2018 MBP to the dock.

The trick seems to be daisy chaining the MBP and iMac through the dock (or through a Thunderbolt Harddrive, as another user reported) instead of connecting them directly.

I thought this but then Pennock pointed me into the direction of 10.14.1 the beta version of Mojave from here https://beta.apple.com/sp/betaprogram/

Since downloading and installing the target mode works like it did before on Sierra no problems 🙂