Cannot select a dropdown value after uploading a file

Scenario - I’ve upload a swagger file to the portal, as soon as file upload is successful, system will enable dropdown and we have to select a field from it. In this case system does not open the dropdown right after swagger file upload.
(I’ve tried with select by lebel / index)

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What is the error message you are getting (if any)? Can we see any code or HTML to check?