Which approach do you use? Database First? Model First?
On my side, I tested your problem with model first. I added or deleted a scalar property, and click Save (not Save All) to save edmx file. Then the entity class changed and saved. Could you please let me know your
steps to reproduce your issue?
In addition, the .tt files automatically change themselves based on edmx to generate corresponding entity class and context class, after you click Save button on edmx.