Newest BIOS update from 8/16 (BIOS 1.5.8) has completely fixed the issue for me. I have tested about 8 hours with no USB problems on the TB16 dock with a latitude 7480. Should be resolved now.
I seem to be having this same problem with a TB16 and a 9560. I have all the latests drivers. I would try to downgrade my BIOS but I can't see where to download the previous one.
Notice a new BIOS 1.3.0 for the 9550.
There is also a recent update of the Intel Thunderbolt Controller Driver, 188.8.131.525, A03 28 Aug 2017
Did anybody try if it is stable and USB the WD15 / TB16 works?
Thanks for the heads up about the BIOS. The driver has been for a while, despite its stated release date. I have it installed already and still have USB issues with the TB 16. Going to try the new BIOS soon.
I installed the new drivers recently and had no problems, until I also updated the BIOS to 1.2.29. That caused the external USB keyboard and mouse to stick (I have used them for many years, including with this computer since buying it). Reverting to 1.2.25 made keyboard and mouse work properly again... except that it deleted the BOOT and I had to create a Add a new UEFI boot to get Windows 10 to boot.
Also, I use BitLocker. It is normal after updating BIOS to have to re-enter the long BitLocker password, since I have that enabled. But after restoring to 1.2.25, it is now necessary to re-enter every time I power up. This is a huge annoyance.
I am using the TB16 with an XPS 15 9550.
Downgrading to 1.2.25 and laptop would not boot, but I recovered without re-installing Windows by Add Boot in BIOS. Got my 9550 running again in less than a half hour, but I was very tense.
For instructions, see:
Look for reply from ben.incani
To make things easier, I am pasting the instructions here:
I have the xps 13 9360 and TB16 dock and am experiencing these problems. Where can I find old BIOS versions? Can't find anything except the newest version on the support site.
I installed BIOS 1.3.0 for the 9550 today (after having problems with 1.2.29, then reverting to 1.2.25, which does not have the sticky keyboard/mouse issue).
I have been using the computer (external USB keyboard and mouse) for about an hour and have seen no sticky behavior, with one exception: after rebooting, at login, if I try to type the password while the system is starting everything up, I have seen some extra keystroke marks. This might be unrelated to the BIOS issue.
When I reverted to 1.2.25, it became necessary to enter the BitLocker ID for every boot. I tried 1.3.0 hoping that that problem would go away. It did not. Dell did post a fix for the Bitlocker ID issue, but it suggested unchecking the USB-C Boot and Preboot options (in System Configuration). These are already unchecked, and I still have this issue, at least with the TB16 plugged in. Have not tried it without TB16, yet.