Emulator

Game Name?
Sonic & Knuckles

Game ID?
MCDE8P

What's the problem? Describe what went wrong in few words.
After launching the game, before showing anything, XFBEncoder::Encode() has this function fail:
hr = D3D::context->Map(m_outStage, 0, D3D11_MAP_READ, 0, &map);
resulting in a panic alert in the next line, followed by an access violation when it tries to read map which is still all zeroes.

What did you expect to happen instead?
Sonic & Knuckles to run (pardon the pun).

What steps will reproduce the problem?
[Don't assume we have ever played the game and know any level names. Be as
specific as possible.]

1. Set External Frame Buffer to Real.
2. Launch Sonic & Knuckles.
3. Wait a few seconds.

Dolphin 3.5 and 3.5-367 are old versions of Dolphin that have
known issues and bugs, so don't report issues about them and test the
latest Dolphin version first.
Which versions of Dolphin did you test on?
4.0-1712 (I think)
Whatever the latest git version was on 27-May-2014.

Does using an older version of Dolphin solve your issue? If yes, which
versions of Dolphin used to work?
I don't know.

What are your PC specifications? (including, but not limited to: Operating
System, CPU and GPU)
Windows 7 x64
Intel Core i7
Nvidia

Are you using the 32 or the 64 bit version of Dolphin?
64 bit

Is there any other relevant information? (e.g. logs, screenshots,
configuration files)
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link here. Use imgur.com for images and pastie.org for logs.]