Thunderbolt Display: audio, camera, etc. not working (USB-C adapter)

I'm connecting a new MacBook Pro 15" (Late 2016) to an Apple Thunderbolt Display using the Apple USB-C to Thunderbolt 2 adapter. 90% of the times, only video works. Ethernet, camera, audio don't work (i.e., no USB). They don't appear listed in Sound preferences or Network preferences, etc. It looks like 99% of the time something goes wrong and the protocol is not negotiated correctly, so only video is available.

I've been suggested by Apple support to delete the "Thunderbolt Display" entry in the Color section of the video preferences and reboot. I tried that a few times, but the problem persists. I even tried resetting the SMC after deleting the entry. No chance. Ethernet, camera, etc. work in say, one reboot on 10—even less.

Dear Apple guys, any idea? I'm connecting a 4000$ MacBook to an expensive monitor using a 60$ adapter, and it doesn't work. Not what I expect from products in this price range.