Why does it say Upgrade Required when I know the data model hasn't changed?

When a transformation is checked out, its target clinical data model is also checked out. But if the transformation checkout is undone, the model checkout is not automatically undone. To undo the model checkout, go to the model and undo the checkout there. Otherwise the transformation is set to Upgrade Required, and the new model version is no different from the old.

When the transformation is checked in, the target model is not automatically checked in, but the transformation is set to Upgrade Required.

Checking out the model with the transformation enables the Cascade Blinding and Cascade Masking features because blinding and masking are properties of the model and the cascade operation is done from the transformation.