Hello,
it depends on PropSaveEvents used for PropSaveMain and creation order of the form and datamodule.
In your case datamodule should be created before Main form and freed after Main form destroy.
You can also store all setting by custom code if you like to use different moment of storing.
See my ComponentDemo or DBDemo application which uses PropSave components and works as expected.
Or provide source code of your demo application and I will check what is wrong.
I hope it helps
Tomas