If the editor does not load when you open up a project please go through the following list for possible solutions;
Can you see the editor parameters in the URL?
Some websites do not allow parameters starting with a specific character (?, #). If you can't see any editor parameters in the URL try to change the starting character and see if it works better after that. You do this by clicking My websites -> click the website that your project is set up for -> click Edit website -> change parameter character and hit Save. Now try to open the project again.
How to manually activate the editor
If you remove all (if any) parameters from the URL and then add ?sg-edit or #sg-edit last in the URL and then hit Enter the website will reload and try to load the Editor. If this works you will get a list of your projects for this website and you can then choose the project you want (see image).
Can you open up a preview for your project?
If you can't even open up a preview window for your project you should check if the script is implemented correctly.
Do you get any errors in the console in your browsers dev tools?
If none of the above solutions work you can open up the browsers dev tools and check the console for error messages. You do this by right-clicking in the browser window and then click on Inspect. This will bring up the browsers dev tools. You then need to click on the Console tab and check if there are any error messages that can explain why the editor does not appear.