What exactly is the issue, as in looking at your screenshot, it seems to work as expected. Feel free to share your workflow to help demonstrate the problem.
Tip for sharing your workflow in the forum
Pasting your n8n workflow
Ensure to copy your n8n workflow and paste it in the code block, that is in between the pairs of triple backticks, which also could be achieved by clicking </> (preformatted text) in the editor and pasting in your workflow.
```
<your workflow>
```
Make sure that you’ve removed any sensitive information from your workflow and include dummy data or pinned data as much as you can!
The only thing I can think of is there might be a hidden character at the start of the string. Can you try with other input and manually setting the summary value.