This bug can be found by modifing the example from Qt and the name of the example project is "custom-mesh-cpp".

I make the Qt3D display a custom mesh with large number of vertices, as below,
for(int i=0;i<100000;i++)
{
vertices.push_back(v0);vertices.push_back(red);
vertices.push_back(v1);vertices.push_back(blue);
vertices.push_back(v2);vertices.push_back(green);
vertices.push_back(v3);vertices.push_back(white);
}

After modification, the program run well in Qt5.10, but has access violation problem in Qt 5.11 and Qt 5.11.1.
I have put the source code project here,
https://www.dropbox.com/s/s3dqc1la0osv20p/untitled.7z?dl=0
Please download it and have a try.
Thank you.