Layer Sync: Quaternion to Matrix conversion failed

Unity Engine
1

I have a Controller with 2 Layers, replicating the same state machines and animations (they just have different Masks).

As the machines got more complex, I decided to use the Sync Layer option (together with Timing).

So the Layers are sync’ed, and all pairs of states have the same anims assigned to them…
… but since doing this, I now regularly get this message in the console (Unity now also crashes regularly):

“Quaternion To Matrix conversion failed because input Quaternion is invalid {-1.#IND00, -1.#IND00, -1.#IND00, -1.#IND00} l=-1.#IND00”

Is this a bug in 4.3.1f1 ???

(Extra Info: I have disabled “atomic” on all transitions)

2

More info: the problem only occurs if both layers use the same animation for the same state.
Removing the animation from the sync’ed layer, there is no error message.
This really does look like a bug.

3

I have create a mini-project demonstrating the problem.
Just press run and click the left mouse button on/off.
The error message will show up in the console.

I think this is a MAJOR issue.

1470337–80789–$layers-bug.zip (194 KB)