Open Radar

 
Summary:

When reconnecting a 2018 15" MacBook Pro to an eGPU while the MacBook lid is closed causes the system to halt. Opening the lid reveals a completely shut down MacBook Pro. To turn it on again I have to hold the power button for a second or two. 

Steps to Reproduce:

1. With the MacBook Pro connected to an eGPU and in clamshell mode (lid closed), go to the eGPU menulet and choose "Disconnect AMD Radeon RX Vega 56" (or whatever)

2. I happen to have two displays connected, so I need to wait until displays have gone black (only takes a couple of seconds).

3. Disconnect MacBook Pro from eGPU. Open lid and use normally.

4. Close lid of MacBook Pro.

5. Reconnect eGPU. 

Expected Results:

Both screens should power back on and I should be able to continue using the computer. 

Actual Results:

Both screens stay dark. Opening the lid of the MacBook Pro reveals it has completely shut down (blank touchbar, keyboard not backlit). Holding down the power button for 2 or 3 seconds starts bootup process. When bootup completes I am told that the system shut down because of a problem.

Version/Build:

MacBookPro15,1 with internal Radeon Pro 560X graphics 
macOS 10.14.3

Configuration:

Mantiz Venus eGPU chassis
Gigabyte Radeon RX Vega 56 Gaming OC 8G Graphic Card
Dell P2415Q primary display in landscape (looks like 1920x1080, default resolution) - DisplayPort connection
Dell UP2715K secondary display in portrait (looks like 1440x2560, default resolution but rotated) - dual DisplayPort connection

SYSDIAGNOSE (taken after crash and subsequent bootup) ATTACHED