Files extracted from an archive have particular permissions that prevent SyncTime from accessing them before the process has completed. Only when the process has completed SyncTime is able to access the extracted files without errors.

There are some workarounds:

• Set a delay directly below the Keep synced in background option. The delay should be higher than the time needed to unzip your archives.
• Pause the sync item before starting the unzip operation and unpause it again when the unzip operation has completed. You can pause alls syncs by toggling the menu item Pause syncs in the File menu or the status item menu.
• If you are only interested in syncing the zip archive, but want to unzip it occasionally without syncing the extracted files, add a filter that matches the extracted file or directory. You can either add a File or directory filter and select the extracted directory in an open panel, or add a Filename filter with Operation set to Exact match and Value to the name of the extracted directory.