The fallback logic in the Document Builder has changed so that when there is not a Jacket Cover in the market that is being used the Document Builder will not fall back to a jacket cover in a different market.
If you were using this fallback logic to populate your jacket covers and are now not seeing them there are two way to rectify this.
The first is to upload the jacket covers into the market that you are using. This can be done through the mass upload that you use or can be done manually. Instructions for manual uploading can be found here. You can use the same images as jacket covers in multiple markets.
The second option is to change the market for that particular element. This can be done using a drop-down menu on the top of the assign/reassign menu. Selecting a different market for a specific element will not change your market or the market for that template. This is where you can change the market for a specific element:
This drop-down menu can be used to include content from all markets for each element, not just Jacket Covers.