I’ve just tried this myself and making a question explicitly non-relevant in a new version of the form does not cause the field in previously submitted submissions to be lost when subsequently exporting the entire data.
In this form I originally had the isParent question with relevant=TRUE. And performed 2 submissions (“test 1” and “test2”). I then updated and redeployed the form after changing isParent to relevant=FALSE
SimpleFormRelevant.xlsx (18.0 KB)
and then did another two submissions (“Test 3” and “Test 4”). Obviously, when I did these later 2 submissions the second question was not shown.
But, as you can see, in the final export the first two submissions remain unchanged.
Simple_Form_Relevant_-all_versions-False-_2025-09-18-21-45-14.xlsx|attachment (8.8 KB)
I’m not sure exactly what you are seeing here, but changing the form relevance should not affect any of the raw data that has already been submitted.
It will, however, ‘hide’ the now non-relevant question(s) should you attempt to subsequently manually edit the submission in Kobo - because Enketo will be using the latest version of the form to perform the edit. This will mean the field will become blanked out when you save the edit (!); eg
But simply updating the form to make a question non-relevant should in-of-itself not cause any existing data to become blanked out in an export, as I showed above.
