Connecting Apple TV HD to a monitor over USB-C port

After more playing around, I now have a workaround whereby using a Mini DisplayPort to VGA adapter instead of one of the Mini DisplayPort to DVI adapters, i.e. an analogue connection to one of the displays instead of digital, seems to work and allows me to have 3 active displays configured like so:

Display 1 connected via HDMI to DVI adapter (into HDMI port)

Display 2 connected via (passive) Mini DisplayPort to DVI adapter into Thunderbolt port 5 (as in the diagram in the above article)

Display 3 connected via Mini DisplayPort to VGA adapter into Thunderbolt port 2.

However, I was hoping to have an all-digital solution as the above Apple article suggests I can, so I'm still hoping someone will come up with a better idea!

UPDATE: This appears to be an issue introduced with OS X 10.9.3. Tried an identical machine running 10.9.2 and the second configuration I tried in the original question worked just fine. Hopefully it'll be fixed in 10.9.4, until then the workaround above is still valid.

The reason why the dual setup isn't working is that you are using MiniDP & HDMI when dual monitors via MiniDP and HDMI are not supported, as noted in the product guide. You will have to use a Thunderbolt-ready monitor with a Thunderbolt cable to allow both monitors to be driven from the dock.

The reason for this is that your dock is being driven by one Thunderbolt port, which does not allow for daisy-chaining displays (as far as the port on your computer is concerned) unless it is Thunderbolt 2 or the newest revision of DisplayPort. If you were to plug your monitor either into the spare Thunderbolt port on your computer (HDMI on the dock) or use the HDMI port on the computer (MiniDP on the dock) both monitors should work as a workaround.