If getting stuck in TWRP, just put it aside and wait for about 2 mins until the screen's off.
Then you'll found your TWRP working perfectly.
I don't know if this is an individual case.
If this isn't, this bug should be reported to the developer team...
"Download" app doesn't work on my Mi2s.
It doesn't start a download when clicking a download link. (http/magnet/torrent...)
Btw, the app name changes from "下載" (Download) to "下載管理" (Download Provider) in the launcher.
I wonder if it matters.