I recently encountered a similar issue and found my solution in a SAS support document. Appending the solution to this answered post in case other users encounters the same problem in future.   Apparently this happens when the program history code is deleted. Why it gets deleted, I have not yet figured out.    Solution:  Make a backup copy of your project and open it Select Tools ► Options ► Program History. Press the Clear Program History button. Uncheck the Enable Program History option. Click OK to close the options window. Save this project and close Enterprise Guide. Reopen the project that you just saved. (To re-enable the program history for the project, just go back to  Tools ► Options ► Program History and check the Enable Program History option.)   Link to SAS support article: http://support.sas.com/kb/56/273.html ... View more