Hi.
Forbidden filename chars on windows are: * " / \ < > : | ?. Shapez is not properly filtering these on other platforms, so they are saved, uploaded via cloud sync, then emit an error when pulled back down on a windows machine.
For example, you can see in the steam cloud_log.txt on windows:
[2025-10-10 00:59:29] [AppID 2162800] HTTP download for file 'tobspr Games/shapez 2/blueprints/Etc/??.spz2bp' from host 'steamcloudquincy.blob.core.windows.net' - Success.
[2025-10-10 00:59:29] [AppID 2162800] Downloaded file could not be written - error 2, internal path 'tobspr Games/shapez 2/blueprints/Etc/??.spz2bp', file path 'C:\Users\****\AppData\LocalLow\tobspr Games\shapez 2\blueprints\Etc\??.spz2bp'
[2025-10-10 00:59:29] [AppID 2162800] Download I/O Operation Failed for file tobspr Games/shapez 2/blueprints/Etc/??.spz2bp
[2025-10-10 00:59:29] [AppID 2162800] Download complete, result I/O Operation Failed