RE: Trouble with XPS 15 9550, USB-C/Thunderbolt 3, and external monitors
Heads up everyone! I was bored for a minute after I just posted and checked out the drivers on support.dell.com. Dell posted a BIOs update that looks like it is the final patch for any left over issues. Today July 5th. Here is a copy of it. I'll update my laptop and report back.
Dell XPS 15 9550 A10 System BIOS
Fixes & Enhancements
2.Fixed LCD flickering when in lowest brightness
3.Fixed After McAfee encrypted, the PCIE NVMe SSD \ SATA SSD can't boot to OS issue
4.Fixed Wake on WLAN takes a long time with Intel 1830/1820A Wireless card
5.Fixed USB audio/mouse may be lag while connected to Dell Thunderbolt Dock (TB15) and Dell Dock (WD15)
6.Support for Windows 10 Enterprise features
7.Fixed incorrect Thunderbolt security level reading from Driver
8.Fixed Touchpad may be lost after Dell Thunderbolt Dock (TB15) device connected
9. Add passthrough MAC address shows on BIOS Setup feature.
10.Fixed System will become shut-down with connected to Dell Thunderbolt Dock (TB15) after S4 Resume.