To fix stuck orders in MMS, do the following:
- Open Shopify admin for the Store
- Go to apps > MMS & Reconnet
- Search for the order
- If it is in pending status with no ability to generate a payload, copy the fullfilment ID and then click on 'Delete'
- Once deleted, search for the fallfilment ID from step # 4 and then press import
- Once imported, go back to the MMS app from step 2
- Search for the fulfillment ID
- Generate MMS payload
- Upload