I see this too. I think when you save and reopen, the zoom defaults to that of the project template that was originally used for the project or to the lens that you used. I do wish Sonar would save state when you hit save - it only saves certain changes. You can test this by- if you save a project then make a musical change the title of the project will get an * next to it to show that it needs to be saved. However, if you save the change then zoom in or out the * will not appear and you will not be prompted to save. I see zoom as a change to the project personally. Apparently, Sonar does not.