Sample Workflow Shared
Combine Multiple Excel Sheets from Multiple Files
This KNIME workflow demonstrates a simple technique to append data from all worksheets across multiple Excel files, even when each file contains a different number of sheets. Perfect for automating multi-sheet data consolidation!
Check it out here 
Combine (Append) Multiple Excel Sheets from Multiple Excel Files with Varying Number of Sheets – KNIME Community Hub
You didn’t include the data in your workflow.
Hi @rfeigel,
Thanks for pointing that out! 
I’ve now updated the KNIME workflow to include sample data so that it’s easier to explore and test the logic. You can find the updated version at the link Combine (Append) Multiple Excel Sheets from Multiple Excel Files with Varying Number of Sheets – KNIME Community Hub.
Appreciate your feedback — it helps make shared workflows more useful for everyone! 
Best regards,
Still doesn’t work. Why not put the files in the data folder with Read From set to current workflow data area?
Dear @rfeigel,
I’ve corrected the setup by placing the files in the Data folder and setting Read From to “Current Workflow Data Area.” Everything is now working as expected. Thank you very much for your guidance!