1. Have the File Picker showing a place where there is at least one folder and a bunch of files. 2. Press Ctrl+A to select everything. 3. De-select the folder so only the files are selected. 4. Press Enter key on your keyboard. Result: Instead of submitting the files, it enters the de-selected folder.
Can reproduce in the file picker.
Even if Ctrl+A is pressed without folders being present, the Enter button doesn't work. However it does work if the files get selected by using rubberband selection. I also noticed that Ctrl+A doesn't select without clicking on the File Picker's background first, which makes it not friendly to use with just the keyboard.