Sparkline were set with a curious challenge when one of our clients raised a problem with the Google Analytics Source/Medium report. The top Source/Medium by sessions was “(not set) / (not set)”. This was very, very unusual. We asked what could possibly cause GA to not recognise Source/Mediums correctly?
After some untangling, we discovered that the blank string had been set as the campaignId in the GA tags. Since GA couldn’t interpret the blank string, it simply saved the Source/Medium as “(not set) / (not set)”.