The automatic line generation process looks at all products that have the selected supplier as their main supplier. This can be configured per product by going to ApeksOPS > Inventory and clicking the product link, which will show this page:

Click “Add Supplier” to link a supplier to the product, and ensure that you set “Main” to “Yes”.

You should also check and set the “Low Stock Threshold” and “Maximum Quantity to Replenish To” here – these are the “Min” and “Max” in the Min-Max process. (Note: changing “Low Stock Threshold” here will also change the equivalent field in WooCommerce, except if the product is a variation. WooCommerce doesn’t support variations having their own thresholds. ApeksOPS does support this, however).