External monitor problem iMac 2017 High Sierra.

The display I’m using is a Dell SE2516H. When I look up drivers, it only lists them for Windows. The Dock I’m using to connect the display via Apple Mini DisplayPort to VGA adapter is a Thunderbolt 3 from OWC. The drivers page is listed here, but it doesn’t say anything about drivers for the Mini DisplayPort. Should I install it anyway? https://www.owcdigital.com/support/software-drivers

Is there an updated driver required for the Apple adapter?

I am confused, what did not work in Serria? If the monitor did not work in Sierra then that is a different issue then the issue most of us are experencing here.

My issue as well as others in this post had working monitors with Sierra and then had some sort of issue after upgrading to High Sierra.

Sorry I misunderstood what you were explaining.

Thanks for that Big64 - have downloaded that... Cant find it now, mind you, but I'm assuming its in there some where doing its thing!

I'm drifting slightly off-topic here, but it is monitor related: has anyone noticed that if you choose your own desktop image, when you reboot, it goes back to the 'default'... Normally - this would be no more than anecdotal, but it occurred to me that if the designers at Apple have begun exerting their own tastes over those of Apple customers, does that not suggest a divergence from the founding philosophy of Apple - that of the ability to express oneself, ok - within a framework identity that was distinct, ie that we bought into the "Apple brand, feel, palette" BUT... the big difference was that the computer served the - especially creative/artistic - human operator, not the other way round..? If I wanted the other way round, I'd have stayed with Microsoft!

Ive got the same problem too - at least I now know its nothing I've done - thats Apple. Where is your Quality and Testing? Not amused.

I look forward to a High Sierra update asap. I, as MANY others now appear also, have a useless external screen. The curser moves across the screen, but it remains black and I can't drag any windows on to it. :-(

And HOORAY!! Checked the monitor (an old HD Ready TV, but did the job admirably), and it had breathed its last. Found another, less old TV last night on a local auction app here in London, and hey presto - this morning, connected and turned on - got an image immediately, and it's been good as gold all day!

I've got a 4th monitor (yep in a studio - even a home one - you need at least 4!) arriving at the end of the week. That'll be the largest numbers of screens I've ever run. I'll post how it goes. So, it might be something Apple just fixed, or the 'displaylink' software Big64 shared with us previously, or running Onyx (for High Sierra) sorted out some permission bottleneck, I cannot tell you. I'm not that 'au fait!' But it being something 'deliberate' by Apple, I think we can scratch that out. I do wish they'd leave us with the last say on desktop images, though. Much as I think that landscape is impressive, I'm trying to do photos for my new website, and want the website backdrop on all monitors. High Sierra keeps changing it back!

This is so much Bullsh*t, I too have the same issue, the mac does not recognize the external screen, what is Apple taking so much money for? I'm not recommending Macs to anyone if this persists. Apple needs to fix this soon.

Got to add a BIG thanks and "GROUP HUG" to the whole Apple Family (that's QUITE a hug!!). I've got 3 monitors fine, 4th due here tomorrow - it'll be the most number of monitors I've ever used!!!

Now... can we PLEASE - APPLE - be allowed to choose our own Desktop images..? xxx

I have a new ASUS display plugged on my iMac 27' (2013), with an HDMI to mini Display port, and I have recurrent issues (in other words: display recognized but unstable or totally black). I tried with my MacPro, same connection: same problem. I tried directly via the HDMI port, and it works well.

So, I agree with you that there's probably some "issues" of connectivity with High Sierra...

I had previously used time machine to go back to working Sierra being unable to resolve the issue with High Sierra. After reading your post I had to try High Sierra 10.13.1. Unfortunately, I am unable to use either display when I have the Thunderbolt to HDMI adapter linking my external monitor. The display on iMac goes blank as well as nothing on my external. I will try a complete power down and the reconnection process now. Haven't tried my MacBook Pro with HDMI to external but I will and report back.

Well, the complete shut-down of iMac didn't work. I am able to use the HDMI out to extend my display normally using my MacBook Pro. I will be glad when this problem is resolved, but for now I think that I will have to go back to Sierra.. I really need the extended monitor for productivity. Good luck everyone, please post if someone thinks they may have found a complete solution for the Thunderbolt / USB-C connector. Just for the record my iMac is a 2013.

Thank you,

Jack

I am running a MBP with 2 external monitors, 1monitor via HDMI cable and the other via MDP-DP cable, after upgrading to High Sierra, it won't recognize the MDP-DP monitor, however the HDMI works fine.

Also when I try to connect the MDP-DP monitor, my MBP reboots.

Believe it is a Apple problem, and would like it resolved ASAP.

+1 - I have three external monitors connected to my 2015 macbook pro, and keep the computer itself closed and in a Henge Dock. The monitors are connected to the two mini display ports and the one HDMI port. Since the macbooks internal graphics can only support rendering two monitors, I use an active adapter to make the third monitor possible.

This worked perfectly before High Sierra. Now only two work.