In order to preview photo galleries inside Blocs preview, Iconic Gallery has to be published at least once to the server. With this, the necessary resources are available on the server in order to be able to load the information about uploaded photos into Stacks preview.

First, check that your project settings contain the correct base URL. If you use a subdomain for testing purposes, the base URL must contain the subdomain also.

Second, place Iconic Gallery Stack on a page of your choice. The folder settings you're entering don't have to be correct in that case.

Third, export the project and upload to your server, or use the integrated FTP upload.

Forth, upload photos for the galleries in the correct folder locations.

Fifth, inside the Iconic Gallery Stack settings, use the correct folder location also. Switch to preview mode, and the photos on your server will be displayed locally inside Stacks preview.