I remember getting a crash in my own RealSense project in the Unity game creation engine earlier this year when trying to use a kiss gesture. So I don't think it's a problem that is exclusive to the R3 version of the SDK. A few of the face gesture settings just seem to be much more likely to cause a crash than others, or not respond at all unless you contort your facial expression into something resembling a horror movie monster..
If you are using the Unity game engine, there are workarounds you can construct to detect a kiss-like action. Otherwise, all you may be able to do is choose a facial gesture that approximates what you want to achieve. For instance, if the two people are in close proximity to each other and the 'Mouth Opened' expression is true.
I am not using Unity3D but the raw C++ API.
The problem is that the crash occurs even if expressions / recognition / pulse are deactivated, eg. I tried and got a crash with only "Detection", "Landmarks", "Pose" being checked in the SDK example. So maybe it's not a problem due to the kissing gesture specifically but to multiple person detection...
Another developer who saw your message has just reported that they also had a crash when at least 2 people face to the camera.
There is an emerging pattern of developers who have problems in R3 when using the Face module in combination with other modules. There are not enough reports yet to confirm this for certain though.
I'm reporting another occurrence of this problem here : SR300 - crash while facetracking multiple people
Our problems look similar, but are not quite the same. Maybe, with the ressource in this thread, you'll be able to solve your problem, or it might help you do more tests and give Intel more data to track down the issue.
This message was posted on behalf of Intel Corporation
I would suggest you to take a look at this link, regarding an issue with the libpxcface_idc.dll library.