More specifically, Frontpage Slideshow will grab the XL image size from a K2 item if the source image is not present for some reason (e.g. deleted to preserve disk space on hosting accounts with limited storage).
This is a maintenance release.
As a reminder, support for RedShop and Tienda will be removed in the next major update of Frontpage Slideshow (v4).
The JoomlaWorks demo site has been updated to use the latest Frontpage Slideshow release. See here https://demo.joomlaworks.net/frontpage-slideshow and here http://demo2.joomlaworks.net (responsive version).
If you have an active Frontpage Slideshow membership, just head over to the Member Dashboard at https://www.joomlaworks.net/members and grab your copy from your "Subscriptions" page.
Or purchase this latest release from just 19.90 EUR. More info at: https://www.joomlaworks.net/fpss
Just upload the new version and it will overwrite the old one.
For more help, please visit the updated documentation page for the extension at: https://www.joomlaworks.net/support/docs/frontpage-slideshow
For support questions please use our Ticket Support System inside the Member Dashboard at https://www.joomlaworks.net/dashboard (active product membership required).