I just wanted to add, that I am experiencing the same issue here. It worked fine before updating to Mac OS 10.12.2. I tried installing the pixelclock patch to see if this changed anything, but had no luck. 

I was getting 4k@60hz in clamshell mode before, now when I use the Adapter without the power cable plugged in, I only get 4k@30 hz, even with pixelclock patched and SwitchresX. 

Have you found any solution yet?

I got it working now. Here’s what I did, although I don’t know what really solved the problem:

I restartet the machine with the adapter and Screen plugged in, but without the power-supply. After that I got 4k@60hz from my Monitor again, but the problem with the power supply persisted.
After having worked for some time like this, I went outside and let the macbook go into sleep-mode, and I turned of my external screen, also I plugged the power in to charge the macbook. When I got back, I woke the macbook from sleep without turning the external screen back on and realized, that it did detect my external screen, since I didn’t get any users to choose from at the login screen (I’m not syncing my screens). I turned my external screen on and everything worked like a charm. 

Maybe you can try playing with the power on your monitor.

I have the same problem with my macbook early 2016.

None of the suggestions solve the problem 🙁

Hi andreleite.

The problem hasn’t been solved entirely for me either. Here’s how I manage to get it working with power supply. 

Plug in everything and leave your macbook running. Let it go into sleep on it’s own. Wait for some time (I don’t know how long exactly, I reckon it needs to go into “deep sleep”) and then wake up your macbook. This usually makes it work.

I opened a ticket with support a while back but did not get any response yet. Maybe you can do the same thing and whatever works, lands here?

i am pushing R&D on daily basis and will keep it up until we can solve this …
Thanks for your patience

Thanks you MST1407