As suspected, I noticed that on your page you had had multiple Klaviyo accounts that are connected to this page.
Please note that integrating one Shopify store into multiple Klaviyo accounts can cause multiple issues and duplicate onsite Klaviyo javascripts can cause errors. To avoid creating duplicate accounts in the future please make sure to click on the Log In button, not the Sign up button when you log in to your account especially when you login via the Shopify App. To make the login process easier you can bookmark this page instead of clicking on a button on our klaviyo.com page or going through the Shopify App. Please ensure you are on the right account and check to see if that is the problem when you think you have suddenly lost all your data.
Thanks for posting to the Community and apologies to hear you’re running into this issue.
Can you confirm that this is the same account that you have always used? Some times, we have found that people create a duplicate account by mistake and for that reason do not see previous work.
On the other hand, can you also go into your lists/segments tab and confirm you see zero users in? I have also opened a support ticket in regards to this since they are better able to take a deeper look into your account specifically.
As suspected, I noticed that on your page you had had multiple Klaviyo accounts that are connected to this page.
Please note that integrating one Shopify store into multiple Klaviyo accounts can cause multiple issues and duplicate onsite Klaviyo javascripts can cause errors. To avoid creating duplicate accounts in the future please make sure to click on the Log In button, not the Sign up button when you log in to your account especially when you login via the Shopify App. To make the login process easier you can bookmark this page instead of clicking on a button on our klaviyo.com page or going through the Shopify App. Please ensure you are on the right account and check to see if that is the problem when you think you have suddenly lost all your data.