If you see the error below in your the Alerts & Comments section of your FBA multi-channel fulfillment order when looking in the Needs Attention status, you will need to follow the below instructions to re-authorize the ZentailCommerce MWS application in your Seller Central portal.
In Seller Central:
Click Settings on the top right of the page.
Click User Permissions on the drop-down menu.
Scroll down to the Amazon MWS Developer Permissions section.
Re-authorize the ZentailCommerce application.