Blank SKUs for variable products

I’m getting blank skus for variations of one product only that I’m noticing. I don’t know how long this has been going on, but at some point the plugin started only sending the parent sku. I removed the parent sku of the item and now it is exporting them blank (in my case not exporting them because I have a rule set to not export if blank). I’m wondering if this is more a glitch in woocommerce from an update? I don’t know why it would affect only the one product.