Master Graphic properties cannot be edited in ECP
If you create a graphic using the graphics dropdown menu, and then upgrade it to a master graphic, it can no longer be edited using the Effect controls window and only in the Essential graphics window if you drag it onto the timeline.
Thank you taking the time to submit this. Can you perhaps tell me a little bit more about what you did? Specifically, what are you seeing in the ECP after you drag and drop a master graphic into the sequence? Do you have the track item selected at that time? Or is it the Master Graphic item in the project that is selected?