Unfortunately the location data is likely unretrievable. It's hard to say what happened, but it sounds like the locations were left at their default values; perhaps the map wasn't visible, or the question wasn't properly linked to the feature layer's geometry. (Edit to add - if it's a web form, is it possible that you have a hidden geometry question, and your users didn't allow their location to be accessed by the browser?)
In the future I'd recommend testing your survey with a variety of devices and browsers before distributing it. For example if it's a web form, try submitting records from a few different browsers on a PC, then try a few different browsers from phones as well.
For now, you'll want to do this type of testing anyway, to see whether you can re-create the issue when sending in the form yourself. That will help you figure out where the issue is.
