I'm trying to save a document, but I'm getting an error ("Error while saving you changes - Click to retry"), but clicking again does nothing, and when I refresh the page, I see that everything was saved successfully. I'm facing the same thing for publishing and unpublishing as well.
After checking the console, I saw that your endpoints return 500 and sometimes 409.
The document used to be saved normally when the custom type was simple, but after adding more fields this error started.