Probably the most commonly planted Magnolia in Indiana is Magnolia x soulageana. A few weeks ago I noticed that not only were there no reports on iNaturalist for Magnolia x soulageana in Indiana but none in the rest of the USA either. Yesterday I found a report of Magnolia not identified to species. It being Magnolia x soulageana, I put the species name on the report.
This is a cultivated species and should be marked as cultivated for that reason. For some species in a given area if the proportion of “casual” (cultivated) observations of a species exceeds wild occurrences it will automatically trigger the site to mark it as cultivated.
Also, cultivated species are fine to upload but they’re not as important as observations of wild species. I am speaking for myself here, but sticking to wild species for the majority of your observations would be the most useful.
You may see what you see if you limit the search to the section https://www.inaturalist.org/taxa/1330821-Magnolia – the hybrid is not grafted to that section, it is grafted to the genus. If you think it should be grafted to the section, please flag the hybrid on iNaturalist directly.