Changing BackgroundItem to ListItem and using contentHeight instead of implictHeight does not fix this problem (instead it screws up height of all the items and they start appearing over each other). It has something to do with the height of tweetView itself as if I scroll down, height of tweetView increases and context menu never appears over list items.

BTW Examples in https://sailfishos.org/sailfish-silica/qml-sailfishsilica-contextmenu.html use BackgroundItem instead of ListItem too.