Thank you for reaching out to the Community! I’m happy to provide some assistance with adding a Compare At value to product variants, to ensure this gets resolved.
As this value should be populating when selecting the edit function, I recommend attempting the following troubleshooting steps to see if this resolves:
Clear Cache and Cookies.
Try accessing from Another Browser (i.e Chrome, Safari, Firefox).
Try accessing the shop from an Incognito Tab.
Attempt using Another Device (i.e Phone, computer, etc).
Try from the Shopify Mobile App.
Alternatively, you can access the Compare At feature for variants through the Bulk Editor. To achieve this, you can:
Head to Products from the Shopify admin.
Select the checkbox next to the item you want to edit.
Select Edit Products.
Locate the Compare At column to add a price for each variant.
Click save.
Please let me know if you have any other questions!