[pvonk]

First, check your preferences to see if the "Return should also save and exit" box is checked.

However, you are right - pressing <enter> doesn't do anything UNLESS you are in the first textfield (title) of Quick entry. If you type a title then press <enter> the action goes into the inbox as desired. But <enter> doesn't work if you are in any other text field, such as start date or context.

Of course you *can* shift-tab from one of these other text fields back to the title and then press <enter>; that works.