When using the built-in Symantec Endpoint Protection Manager (SEPM) utility "Database Back Up and Restore" with a large database size that results in a zip file greater than 4 GBs, the resulting zip file will appear to be corrupt by any other zip utility.
The SEPM's Backup Utility uses custom technologies to create a backup file that is not able to be viewed or opened by third party compression utilities. The zip files we create are invalid from any other tool's perspective. The resulting zip is no longer using the standard zip format and cannot be fully used by these tools.
This is currently working as designed. Though these .zip files cannot be opened by common third-party tools, the files are not necessarily damaged or corrupt. Backups created using the SEPM's built-in backup utility that are larger than (or that result in a zip file that is) 4 GBs will appear corrupt or invalid to third party zip utilities. The SEPM's built-in restore utility is able to read and restore its own backups successfully and does not have a size limitation.