If the model contsains two schemata with same GUID but different fields, one of them will be deleted when upgrading to 2025. For instance, one in model and other one on a loaded family. To test if there is a conflict in Revit 2024, you can open the model with audit. If you see the Schema conflict dialog, it means that there is a conflict. In this case, it’s working as expected. If not, please provide your model so we can take a look to see what’s happening.
