After dbimporting a model, I noticed that ObjAttributes inside the entities are saved in XML in the order that is not alphabetical. Opened the same model in the Modeler, made some changes, saved again. The order is still not alphabetical. The rest of the model objects (DbAttributes, entites, etc.) seem to be sorted correctly.
Opened the same model in CM 4.0.1 (after manually downgrading it to be compatible with the older modeler). Saving in 4.0.1 restores alpha ordering for attributes. So this is a new bug.