@NagaSaiJ Yes , clicked on Save and screen refreshes , data is still there but on closing the case (nothing pop up to ask about discard the changes)and the case is closed.But the data is absent from text field on again opening the case.
Make sure below things are happening to make it work .
Make sure On change for the property field , you have defined accordingly .If it has no dependency with any other fields , you can have simply have OnChange-PostValue
This will make sure value is posted to temporary memory .
If you are closing the case with custom Close/Cancel button make sure you have configured the OnClick-CancelWorkitem or which ever appropriate.
Also there is an option to close the case from the cross mark , which is OOTB.
Now when there are any uncommitted changes on the screen .(Value saved to temporary memory and not committed)