It could be a has a chance of theme or plugin conflicts. You can disable all your plugins except Dokan and switch to a default theme of WordPress like – Twenty Twelve, Twenty Thirteen, Twenty Fourteen and let me know the results.
I haven't changed the theme or any plugins before and after the new Dokan update. And the background of my front page was working perfectly before the update. I just don't want to loose my work by switching to a different theme like twenty fourteen.
I am using Zerif Lite as theme. It's very strange because when I use Safari the background works fine, but when I switch to chrome or mobile the glitch will appear. on both browsers the empty cart >return to shop button doesn't work.