You'll have to edit them in Shopify to get them approved and synced. I'm so sorry that you have so many products to do this to but making an edit and then saving it does fix this issue. Hopefully it doesn't take you too long!

For everyone else searching for the answer to this - THIS WORKED. I feel for you if you have hundreds of listings but I was having the same issue and simply adding a space somewhere in my listing and saving it again moved it over to pending and then ...