'After synchronizing the database...' Does this mean you have copied the database to a new environment? If so, note that files and images are not stored in the database, but are stored in the server file system, so you also need to copy these files to the new server to be able to view them.
You may need to look at the Uploaded files path in your runtime configuration to locate these files to copy.
What was the synchronization you did actually? What were the changes you made to this image entity?