from_iterable broken, or is it my mistake?

[ZmeiGorynych]

I've written a merge_sorted function using aioreactive idiom (it returns an async iterable), and it works fine with async for (see attached notebook).
However, when I try to convert it into a source using from_iterable, that doesn't work at all (also in attached notebook). Is it a bug in from_iterable or am I doing it wrong?
Thanks a lot!
aioreactive merge_sorted.zip