Thanks, frank18! I'll add a note to the top of the plugin's readme to suggest that permissions on that newly-added folder might need to be checked. What are your host's default permissions?
That problem happened locally (local Linux dev server on my computer) - entirely my fault. Had to tweak some settings so it does not bugger me again.
On the live server it worked instantly as permissions are automatically assigned to 755 (folders) and 644 (files).