I have had this happen when the form item has been moved to another folder in my content, as well as when I've changed things with the survey map. Do either of these apply to your situation?
Hi OmarDeLaRiva, what S123 Connect version are you working with ?
I encountered the same problem with version 3.11 (or 3.12, not sure...) when I was republishing a survey with repeats AND where my only updates were inside the repeat section.
Turns out the solution was to add a question into the main table of the survey as well, re-publish the survey, then edit again the survey to delete the useless field created.
Hope that can help, Cheers!