Unable to attach files to Deck cards

When I click the attachment icon in a card the “choose attachment” pop up window is empty, leaving me without any attachments to choose from.

I get the following in the log:


This is the contents of main.php:

 * @copyright Copyright (c) 2018 Julius Härtl <jus@bitgrid.net>
 * @author Julius Härtl <jus@bitgrid.net>
 * @license GNU AGPL version 3 or any later version
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * GNU Affero General Public License for more details.
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.

style('deck', 'globalstyles');
script('deck', 'deck');


It worked for a while after the latest update but I have the issue again.

OK, turns out I am a bit dense.
I was trying to attach files using the paperclip icon next to the description and there were no attachments to choose.
But I realize now that I need to click on the attachments tab at the top of the details pane to upload the attachment, then I can choose what attachment to see with the little paperclip at the description.