Understanding the 'Customers who haven't purchased' section in Shopify reports?

[LT6]

Hello,

I need help understanding the customer segment report in Shopify, specifically the "Customers who haven't purchased" section. It seems a bit off that 97% of my contacts are labelled as customers even though they haven't made a purchase. Could this issue be related to our recent migration from Magento to Shopify? Additionally, I'm curious about how Shopify generates these reports. Are these records automatically captured and categorised by Shopify, or is there a process I need to initiate?

Any insights or assistance would be greatly appreciated. Thank you! Emma