@Anonymous
In this particular case I provided, we are shorting the EditForm functionality by directly altering the Update property. What this means is that whatever value is in the saveStatus variable WILL be written when you SubmitForm. It will, however, NOT display on the screen at that point in time. If you were to look at your data list, you *should* see the value has been written there successfully. If you were to then Edit, in the EditForm, that same record, it *should* show you the correct value.
My assumption was that you were not displaying the status, but simply forcing a status to it.
If you want to display the value as well, then consider the following changes:
1) Return the Update property of the DataCard to the original formula (most likely DataCardValuexx.Text - replace xx with the appropriate number).
2) Change the Default property of the DataCard to the following:
Coalesce(SaveStatus, ThisItem.Status) or whatever the name of your field is (assumed Status)