Submit button shows Preview as label

I have a Preview widget and a Submit button in my form - and these labels are visible in the design view.

However, when the form is being used to submit data, both buttons show Preview as the label - even though no changes were made to either recently.

Any idea why this is happening and how it can be fixed?

You are actually using 2 submit buttons in your form. I think that caused the confusion. Rename the first submit button to "Submit" instead of preview and then delete the second submit button. That is not necessary.

Example:

Using the "Preview Before Submit" widget, it will automatically turn the submit button into a preview button. Once you click the preview button, you'll see the final submit button on the preview page.

Hope this clears the confusion here.