The only thing that immediately comes to my mind is for you to check the SharePoint Integration settings and see what your "On Save" is configured to do. If you're using multiple screens and multiple forms, you'll need a way of defining when a user is in an Edit Screen vs. a New Screen. I have multiple screens/forms in one of my integrated forms, so in SharePoint Integration > Advanced> OnSave my code looks like this:
If(SharePointFormMode="CreateForm", SubmitForm(NewForm), If(SharePointFormMode="EditForm", SubmitForm(EditForm), If (SharePointFormMode="UserEditForm", SubmitForm(UserEditForm), If(SharePointFormMode="NotesForm", SubmitForm(NotesForm1))))); RequestHide()
The variable SharePointFormMode is set to each screen's OnVisible property, that way if a user clicks "Save," SharePoint Integration knows which form to submit. If you haven't configured this to work with multiple screens (new and edit), you should check if that OnSave your "new" form is being submitted and not your "edit" form.
Where SharePointDataSource is your SharePoint source list. This manually refreshes the forms connection to the SharePoint list and gets it working again. This, in my experience, wasn't necessary until last week--my forms were working fine and then suddenly they weren't.