I am creating a web map with locations which have pictures attached to them. I have a CSV file with the locations and their thumbnail url and regular-sized photo url, which I took from Flickr. They are shared publicly. I created a shapefile from the CSV file and then added to a web map. I followed this link to customize the pop-ups to show the thumbnail image:
But my thumbnail shows up like this (when I click on it, it directs me to the the regular-sized photo in Flickr).
I am not sure why the thumbnail image does not show up.