RenderTexture::setVirtualViewport() misses a lot of pixels and has wrong offset

[Nyrio]

• cocos2d-x version: 3.16
• devices test on: Windows 10
• VS version: Visual Studio Enterprise 2017

I wanted to capture a part of my scene with a code similar to the following (the design resolution is 1920*1080):

unsigned int SIZE_X = 960;
unsigned int SIZE_Y = 540;
unsigned int POS_X = 100;
unsigned int POS_Y = 100;

RenderTexture* texture = RenderTexture::create(SIZE_X, SIZE_Y);
texture->setVirtualViewport(Vec2(POX_X, POS_Y),
                            Rect(0, 0, 1920, 1080),
                            Rect(0, 0, SIZE_X, SIZE_Y));

texture->begin();
this->visit();
texture->end();

texture->saveToFile("test.png", Image::Format::PNG);

I've tried a lot of different combinations of parameters, but whatever I do, at most the pixels from the rectangle 0, 0, SIZE_X, SIZE_Y are captured, the rest is filled with transparent pixels. Also the offset is wrong.

Here is the result of the code above for a mockup scene, where red means transparent pixel:

All the pixels that I have displayed in red are empty and they shouldn't, and the offset is wrong.