Where do the collections go in 2.8+ when you hit Ctrl-G to make a group? When I press Ctrl-G, the manual says it creates a collection with the selected items.

The screenshot shows my experience: select some meshes, press Ctrl-G, and I get a dialog box at the lower left.... and no other obvious effect. I dug around in the raw blend file using python and found I appear to have been creating collections with these commands, but they don't appear in the outliner? How does one use the hotkey to create a  usable collection?
Okay after a lot of digging it appears that Ctrl-G not creating a usable collection is actually known by the developers: Blender developer discussion thread.

Some of the devs on that thread say it needs to be fixed since the "Create Group" hotkey does nothing perceivable by the user. Others appear to want to leave it the way it is so that it can be used for a new "Common groups" feature when it is implemented. The discussion has been going on for about half a year and the current status appears to be that Ctrl-G does not do what one would expect from reading the documentation. At least I'm not missing something obvious.