Hi there, are you referring to missing values in data exports? If so, I am not sure I've run into that before. I believe if a respondent did not reach the question or indicated an answer option that was marked "Exclude from Analysis", then that value will be blank in data exports.
If a respondent saw the question but did not answer it, it will also be blank unless specified differently in the data export options. Seen but not answered questions can be recoded to "-99" and multi-value fields can be recoded to "0"
https://www.qualtrics.com/support/survey-platform/data-and-analysis-module/data/download-data/export-options/