External monitor not detected by Bootcamp

I ran a number of tests with a combination of devices attached to my Macbook Pro Thunderbolt ports:

1. Apple TB2-to-TB3 adapter connected to Caldigit T3 dock and HDMI monitor connected to the dock's Displayport using a Caldigit Displayport-to-HDMI adapter
2. Mini-display port-to-HDMI adapter connected to HDMI monitor (nothing else attached)
3. Thunderbolt-to-Ethernet adapter connected to Ethernet cable (nothing else attached)
4. Mini-display port-to-HDMI adapter connected to HDMI monitor and Thunderbolt-to-Ethernet adapter connected to Ethernet cable
5. Mini-display port-to-HDMI adapter connected to HDMI monitor and Apple TB2-to-TB3 converter connected to Caldigit T3 dock (no monitor connected to dock's Displayport)
6. Thunderbolt-to-Ethernet adapter connected to Ethernet cable and Apple TB2-to-TB3 converter connected to Caldigit T3 dock (no monitor connected to dock's Displayport)

Test #1 is the original problem that started this post. When running macOS Catalina, everything on the dock (USB, Ethernet, Audio, Video, eSATA) works as expected. When running Windows 10 Bootcamp, everything except video works. I get a blank screen as if the monitor is not receiving a signal.

Tests #2 and 3 work fine whether running macOS or Windows. I thought I had an issue with video when running Windows so I started another post. However, I realized that the issue was caused by a faulty mini-display port adapter.

I ran Tests #4-6 to see if there were any issues with running devices on both Thunderbolt ports (my laptop has two of them). Test #4 worked all of the time when running macOS and most of the time when running Windows. I estimate that 9 out of 10 times the video worked running Windows. For the times that it did not, shutting down and re-starting made the video work. I am not sure why there was some flakiness with Windows.

Test #5 had mixed results when running macOS and Windows. The HDMI monitor connected to the mini-display port adapter worked sometimes and other times it did not. It did work a lot more often when running macOS than Windows, but neither was very stable. The Caldigit dock (no monitor attached) worked every time.

Test #6 worked when running both macOS and Windows.

Based on Tests #1 and 5, it appears that Bootcamp Windows's Thunderbolt 2 driver does not play nice with video data when the Apple TB2-to-TB3 adapter is attached. When a simple HDMI adapter is used (Tests #2 and 4), the Thunderbolt port connects to the HDMI monitor as expected. So, unless Apple decides to update the TB2 driver to work with video while using the TB2-to-TB3 adapter, it looks like I will have to connect my monitor to the Macbook's HDMI port instead of the Caldigit's Displayport.

Loner T,

The mirroring setting did not affect the reporting of the connection type.

I tried a few other things. First, I connected the monitor to the TS3's Displayport using the DP-to-HDMI cable and ran the System Report. It identified the connection type as HDMI or DVI:

Next, I disconnected the TS3 dock and connected the monitor directly to the HDMI connection on the laptop. The System Report was the same as the very first one I posted - it does not show the connection type for the external monitor.

I am not sure why the system does not report the connection type when the monitor is connected directly to the laptop's HDMI port.

Loner T,

Both Catalina and Bootcamp work perfectly with the built-in HDMI connector attached directly to the monitor. That is the way I was connected before I obtained the Caldigit dock. I was hoping to eliminate having to plug/unplug the laptop from the monitor when I wanted to move it.

I had 5 cables (USB, TB for Ethernet, HDMI, Speakers, Power) plugged into my laptop when it was "docked"; I was hoping to get down to two (TB to Caldigit dock, Power). When I am running Catalina, the dream is realized. Unless I figure out something with Bootcamp and the DP port on the Caldigit dock, I will have to add the monitor connection again. I thought about getting a TB3-to-HDMI adapter and connecting it to the Caldigit dock to see if that would work with Bootcamp, however that is adding another adapter to the chain. Another thought is to get a USB-to-HDMI converter and connect that to the Caldigit. The USB connection back to the laptop might be a bit "cleaner" so maybe the signals will flow properly.

Thoughts?

Loner T,

I am using an original Apple TB3-to-TB2 adapter and an original Apple TB(1/2) cable.

You are probably right about the Caldigit TS2 being a better fit since it would eliminate a couple of adapters in the chain. However, I obtained the TS3 in a really good deal so I was hoping to make it work. Worst case, I will have to continue plugging the HDMI cable directly into the laptop when using Bootcamp. Not ideal, but better than it was.

Let me know if you think of anything else for me to try.

Thanks!

Yes, it is an external drive connected to one of the eSATA ports on the TS3. I also have a USB keyboard, mouse and camera connected to one of the TS3's USB ports via a 4-port hub, an Ethernet cable connected to the TS3's Ethernet port and a set of speakers connected to the TS3's Line-out jack. Do you want to see screen shots of those connections in System Report?

Hi Loner T,

For some reason, my System Report does not identify the connection type of the my monitor (E248W-1920) that is connected to the HDMI port. It identifies the built-in screen as "Internal", but it shows nothing for the external monitor.

I notice that your monitors are not mirrored but mine are. I wonder if the report will show the connection type if the monitors are not mirrored. I'll try that and report back.

Thanks!

Loner T,

It's been a while, but I have some new information on my issue. I got my hands on a StarTech TB3DK2DPPD dock; I wanted to test it to see if my issue was related to my machine or the dock. I connected to the dock with the TB3-to-TB2 connector just like with the Caldigit unit. I got the same results as before - everything works perfectly when running macOS Catalina but the display does not work when running Windows 10 Pro.

Clearly, the machine is technically capable since it works under macOS so it seems to be a software issue, specifically the Bootcamp Thunderbolt driver as you suspected earlier. Is there a way to tell if I am running the latest Thunderbolt driver for my 2013 Macbook Pro? Device Manager identifies it as an Apple driver, Version 5.1.4.0, 2/23/2015.

Any other ideas?

Thanks!

The saved monitor details impact both macOS and Windows? How do I delete them?

When you say, "connect the monitor directly first", do you mean connect it to the native HDMI port on the laptop or use a Thunderbolt-to-HDMI adapater to connect it?

Hi Loner T,

Here is my model: MacBook Pro (Retina, 13-inch, Early 2013). My laptop has the 3.0GHz i7 processor.

Thanks!