Mix1 lithium, no sim card, via wifi:
Google Play: "waiting for network".
Everything else seems to work.
Edit:
Other downloads via Download app also do not start, same as Play Store.
When I download a file from within Firefox, I get a choice:
Download via Firefox or via Download app.
Via Download app gives same problem as with Play Store.
Cleaning app data in Download app resulted in one download starting, after question about limit.
But second download waits as before . . .
Download via Firefox works normally.
Edit 2:
Above was done with "unlimited" set in Download app.
Download will never start.
Now I tried setting a limit "100MB" in Download app.
Here I get a question for each download, if I choose "Download now" the download will start.
This works also in Play Store.
So the bug seems to be connected to the "unlimited" setting in the Download app.