I think you are using the insiders build here is the right setting ,I had the same problem and it worked for me.
"notebook.output.textLineLimit": 500
edit: this will also work for the stable version
I think you are using the insiders build here is the right setting ,I had the same problem and it worked for me.
"notebook.output.textLineLimit": 500
edit: this will also work for the stable version