Can't edit or create new products via spreadsheet upload

So I finally figured out how to successfully download my product listings, and then make changes or create new products and variations. The very next day the page is different and won't allow me to upload it. It now has a dropdown box to choose what I'm uploading, but there is no Multi-marketplace listing template. Anyone else having issues with this? Is there a different/better way for me to use my existing listings to create new ones via spreadsheet? Selling shirts and have 48 variations for each design, so spreadsheet seems to be the only viable way. These are my brand items so I'm the only seller with amazon creating the ASINs. Thanks for any help.