2019 MacBook pro - external monitors

It's possible that some part of the MacBook Pro graphics hardware has failed.

If you're using the same cables, swap those for some new known-good cables. Cables can and do fail. Probably not the issue here, but cables are seemingly the cheapest parts left to swap here.

I'd avoid port replicators and docks generally—any that do not explicitly document support for your intended configuration, that is—as you're otherwise just adding complexity and debugging into the mix.

General support info: Use an external display with your MacBook Pro - Apple Support

From the tech specs: Simultaneously supports full native resolution on the built-in display at millions of colors and:

• Up to two displays with 6016‑by‑3384 resolution at 60Hz at over a billion colors
• Up to four displays with 4096‑by‑2304 resolution at 60Hz at over a billion colors

Your existing displays are all well within the supported resolutions.

Your old genuine ThunderBolt should support two displays. it may have failed, or one port on it may have failed.

In order to support up to TWO hardware-accelerated displays on one cable out of the Mac, that cable mist be a genuine thunderBolt cable from a genuine Thunderbolt port on the Mac, and the first device (Dock or Display) must be a genuine Thunderbolt device.

USB-C docks do NOT support multiple hardware-accelerated displays on a a Mac.

if you are using only show-to-change data such as program listings, spreadsheets, or stock quotes (definitely NOT Games or full-motion Video) there are some add-ons that can be used, with substantial compromises.

DisplayLink technology creates a "fake" display buffer in RAM, sends the data out over a slower interface to a stunt box with DisplayLink custom chips that put that data back onto a "legacy" interface. It is not a true "accelerated" display, and it can suffer from lagging. Just adding the DisplayLink Driver is not adequate to get a picture -- you need a DisplayLink "stunt-box" or a Dock that includes DisplayLink chips.

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It may be acceptable for a second display showing slow-to-change data such as computer program listings, stock quotes, or spreadsheets, but NOT for full motion Video, not for Video editing, and absolutely not for gaming. Mouse-tracking on that display can lag, and can make you feel queasy.

In a pinch, it may even play Internet videos (as one user put it) “without too many dropped frames".

The Apple standard for its built-in hardware-accelerated displays, makes them suitable for full-motion video for production/display of cinema-quality video with NO dropped frames, and NO dropouts or partial-blank scan lines due to memory under-runs or other issues. This requires a hardware rasterizer/display-generator for each fully-accelerated display.

If you are only doing program listing and stock quotes and other slow to change data, DisplayLink can work for you, but requires you to make some strong compromises.

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It is really nice to know that you can use a DisplayLink display if you MUST have an additional display for some of the types of data I mentioned. But that is NOT the same as the computer supporting a second, built-in, Hardware-accelerated display.

These displays depend on DisplayLink software, and are at the whim of Apple when they make MacOS changes. There have been cases where MacOS changes completely disabled DisplayLink software, and it took some time for them to recover.

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I think the Big Surprise for a lot of Hub/Dock buyers is that they thought they were getting a "real" display, but actually got a DisplayLink "fake" Display. If you got what you expected in every case, I would not use such pejorative terms to describe DisplayLink.

Once you understand what the compromises are, you can make an informed choice about whether this solution works for you.

Some users blithely assume that if they can connect a display, it will be 'good to go' for editing videos and playing intensive games. In my opinion, the technical marketing behind most DisplayLink devices is inadequate.

That is why I feel obligated to thump on it, admittedly pretty hard.

"If you got what you expected in every case, I would not use such pejorative terms to describe DisplayLink."

This solved my issue as well! just wanted to add a link to the download https://www.dell.com/support/kbdoc/en-us/000125234/dell-displaylink-docking-stations-and-macos-support

Downloaded and started up immediately!

@arn_norseman Are you using an Intel chip? So right now is everything working fine for you? I have a I9 chip and facing the similar issue. I can see the content in dual monitors but cannot see video for some content. It is just grey background.

I just wanted to check if you are using Belkin or Thunderbolt.

bobby_aryan wrote:

@arn_norseman Are you using an Intel chip? So right now is everything working fine for you? I have a I9 chip and facing the similar issue. I can see the content in dual monitors but cannot see video for some content. It is just grey background.

I just wanted to check if you are using Belkin or Thunderbolt.

DRMed video doesn't always play well with DisplayLink and the like. If you are trying to view, say, video from a Netflix streaming subscription on a monitor connected via DisplayLink, the DRM might prevent you from seeing the video.

Make an appointment with Apple Support, and bring it in. I'd guess that Apple will suggest just the Mac be brought in and tested, as they're not going to support all the add-ons here.

DRM means Digital Rights Management -- an encryption system for commercial copyrighted content.

Yeah but I am watching content from Udemy. Some of the videos are playing some are not. And the audio is playing for all of them. It is just the grey screen.