Do you work with multi body Sheet Metal?
But just one Flat Pattern in the feature manager instead of many.
To fix it just make sure you have this setting on in SolidWorks.
1. In an open part, go to Tools > Options > Document Properties > Sheet Metal
2. Check the option “Create multiple flat patterns…. ” under Flat pattern options and hit OK
3. Rebuild your part to get the required result.
4. For future, you may set the option in your part templates.