Keyboard focus becomes trapped after adding files to the Uploader

After using the keyboard to add a file to the Exporter, keyboard focus becomes trapped somewhere - there is no focus styling on any element on the page, tabbing does not change focus to any element on the page, and pressing Enter doesn't do anything.

To reproduce:
1. Load Decapod Exporter
2. Using keyboard, tab to the "Browse files" button.
3. Press enter to bring up the file browser.
4. Select a file.
5. Notice that the focus is now trapped.

The problem doesn't appear if the user opens the file browser and then closes it without selecting a file.