This issue might be due to how the formula in your merged column is set up. The formula may be assuming there's a response for every row, which isn't always the case. To fix this:
1. Add extra logic to your formula, like "if {{response}} exists..."
2. This will ensure the formula only acts on response data when it exists
To merge columns in Clay:
1. Click "Add Column" > "Merge columns"
2. Input the formula to combine the desired columns
If you need more help, you can request human assistance by clicking on "Talk to a person".