Examining the Security properties, it appears that the difference between the forms I am able to save and the ones I am not able to save is that the ones I am not able to save have "Signing" set to "Not Allowed" and the ones I am not able to save are set have "Signing" set to "Allowed." In previous years, f1041sd.pdf had "Signing" set to "Allowed" and now it does not. All forms, including the ones that cannot be saved, have "Filling of form fields" set to "Allowed."