Trace line wont hit landscape with custom trace channel

I created new landscape and changed collision on parent, but it doesnt affect LandscapeStreamingProxy, when I change collision of each one of them it is working. Now what i dont understand is that why changing collision setting of parent “Landscape” wont affect children “LandscapeStreamingProxy”.
Whan I update mesh i updates all,butnot in collsion. Is this expected behaviour?