I have a Google Sheet with URLs to images, which are then synced to Google Drive.
If I sync single files to Google Drive it works, but when there are multiple the files are synced as a zip file and they loose their file extension.
How to solve this ?
Welcome to the Community, 
It looks as though you’ve selected multiple file links in a Upload File (Google Drive) action? That action is only intended to upload a single file at a time so I wonder if that’s what’s causing it to loose the file extension. Can you try selecting just one file link from the Google Sheets trigger and see if that uploads the file correctly?
If it does, then I’d recommend putting that Upload File action inside a loop to allow it to run that action multiple times (for for each selected file). If you’ve not worked with loops in Zaps before you can learn more about them here: Loop your Zap actions
Keen to ensure you’re all set so please keep us updated on how you get on with this! 
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