inconsistent size of MTLRenderCommandEncoder during orientation change

In a iOS metal app, I render on a mtkView on a backround thread. I get the current renderDescriptor from the view using mtkView.currentRenderPassDescriptor. I use that renderDescriptor to create a MTLRenderCommandEncoder. That MTLRenderCommandEncoder sometimes have inconsistent size (width, height) during orientation change : _width and _height are different than the size of stored in the currentRenderPassDescriptor. This causes problem when using setScissor method :

failed assertion `(rect.x(0) + rect.width(1792))(1792) must be <= render pass width(828)’.

So my questions are :

• why those 2 sizes are different ? Where does the second size come from ?
• How can I access this second size (MTLRenderCommandEncoder->_width) as it seems the “real size” used to validate the setScissor method?

This is a summary of the code :

MTLRenderPassDescriptor* renderPassDescriptor = view.currentRenderPassDescriptor;
renderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionClear;
renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0, 0, 0, 1);
id renderEncoder =
[commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];

CGFloat colorAttachementWidth = _passDescriptor.colorAttachments[0].texture.width;
CGFloat colorAttachementHeight = _passDescriptor.colorAttachments[0].texture.height;
MTLScissorRect rect;
rect.x = 0;
rect.y = 0;
rect.width = colorAttachementWidth;
rect.height = colorAttachementHeight;

[renderEncoder setScissorRect:self.scissorRect]; // -> that will trigger the assertion

This is the description of the MTLRenderCommandEncoder when I get the assertion :

-> 
    label = MyRenderEncoder
    device = 
        name = Apple A12 GPU
    descriptor = 
        Color Attachment 0
            texture = 
                label = Drawable
                textureType = MTLTextureType2D
                pixelFormat = MTLPixelFormatBGRA8Unorm
                width = 1792  // <——————————————————— this size is not consistent with the size below
                height = 828
                depth = 1
                arrayLength = 1
                mipmapLevelCount = 1
                sampleCount = 1
                cpuCacheMode = MTLCPUCacheModeDefaultCache
                storageMode = MTLStorageModeShared
                resourceOptions = MTLResourceCPUCacheModeDefaultCache MTLResourceStorageModeShared
  …
            level = 0
            slice = 0
            depthPlane = 0
            resolveTexture = 
            resolveLevel = 0
            resolveSlice = 0
            resolveDepthPlane = 0
            loadAction = MTLLoadActionClear
            storeAction = MTLStoreActionStore
            storeActionOptions = none
            clearColor = (0 0 0 1)
            yInvert = NO

      
        ...

        Depth Attachment:
            texture = 
    label = Render Depth
    textureType = MTLTextureType2D
    pixelFormat = MTLPixelFormatDepth32Float
    width = 828  // <——————————————————— this size is not consistent
    height = 1792
    depth = 1
    arrayLength = 1
    mipmapLevelCount = 1
    sampleCount = 1
    cpuCacheMode = MTLCPUCacheModeDefaultCache
    storageMode = MTLStorageModePrivate
    resourceOptions = MTLResourceCPUCacheModeDefaultCache MTLResourceStorageModePrivate 
    usage = MTLTextureUsageRenderTarget