vt320 displays nothing

[evert]

Dear blessed team,

I'm working on a relatively simple terminal application with 3 boxes. The goal is to make a menu-driven interface for websites. But, I want it to be able to run on a VT320 amber terminal hooked up to a Raspberry Pi.

My $TERM is set to vt220, but the screen just clears and stays dark. There is just a cursor at the top-right.

How can I start debugging this? It works fine on my modern terminal

My program broadly looks like this:

  const screen = blessed.screen({
  });

  screen.title = 'HyperCLI';

  const titleBox = blessed.box({
    width: '100%',
    top: 0,
    height: 1,
    /*
    style: {
      bg: 'green',
      fg: 'white',
    },*/
    align: 'center',
  });

  titleBox.setContent('HyperCLI');
  screen.append(titleBox);

  const uriBox = blessed.box({
    width: '100%',
    bottom: 0,
    height: 1,
    /*
    style: {
      bg: 'green',
      fg: 'white',
    }*/
  });

  screen.append(uriBox);

  cpmst contentBox = blessed.box({
    top: 1,
    bottom: 1,
    left: 0,
    right: 0,

    /*
    style: {
      fg: 'green',
      bg: '#000',
    },
    */

  });

  screen.append(contentBox);
  screen.render();