Beginners question: Emoji not working

Hi, I'm a new jekyll/spaceship user, and have enabled the plugin, and it definitely is working because my mermaid diagrams work now. However my emoji's aren't rendering. I have nothing specific in my _config.yml, I'm using the defaults. I tried :+1: and ✅ and :x:, and none of them are rendering. Unfortunately, I have no idea how to debug any of this.

Any tips on how to get it working?

I'm using this in local dev mode, and here's my gemfile contents:

GEM
  remote: https://rubygems.org/
  specs:
    addressable (2.8.0)
      public_suffix (>= 2.0.2, < 5.0)
    colorator (1.1.0)
    concurrent-ruby (1.1.10)
    em-websocket (0.5.3)
      eventmachine (>= 0.12.9)
      http_parser.rb (~> 0)
    eventmachine (1.2.7)
    ffi (1.15.5)
    forwardable-extended (2.6.0)
    gemoji (3.0.1)
    http_parser.rb (0.8.0)
    i18n (1.10.0)
      concurrent-ruby (~> 1.0)
    jekyll (4.2.2)
      addressable (~> 2.4)
      colorator (~> 1.0)
      em-websocket (~> 0.5)
      i18n (~> 1.0)
      jekyll-sass-converter (~> 2.0)
      jekyll-watch (~> 2.0)
      kramdown (~> 2.3)
      kramdown-parser-gfm (~> 1.0)
      liquid (~> 4.0)
      mercenary (~> 0.4.0)
      pathutil (~> 0.9)
      rouge (~> 3.0)
      safe_yaml (~> 1.0)
      terminal-table (~> 2.0)
    jekyll-feed (0.16.0)
      jekyll (>= 3.7, < 5.0)
    jekyll-sass-converter (2.2.0)
      sassc (> 2.0.1, < 3.0)
    jekyll-seo-tag (2.8.0)
      jekyll (>= 3.8, < 5.0)
    jekyll-spaceship (0.10.2)
      gemoji (~> 3.0)
      jekyll (>= 3.6, < 5.0)
      nokogiri (~> 1.6)
      rainbow (~> 3.0)
    jekyll-watch (2.2.1)
      listen (~> 3.0)
    just-the-docs (0.3.3)
      jekyll (>= 3.8.5)
      jekyll-seo-tag (~> 2.0)
      rake (>= 12.3.1, < 13.1.0)
    kramdown (2.4.0)
      rexml
    kramdown-parser-gfm (1.1.0)
      kramdown (~> 2.0)
    liquid (4.0.3)
    listen (3.7.1)
      rb-fsevent (~> 0.10, >= 0.10.3)
      rb-inotify (~> 0.9, >= 0.9.10)
    mercenary (0.4.0)
    nokogiri (1.13.6-x86_64-linux)
      racc (~> 1.4)
    pathutil (0.16.2)
      forwardable-extended (~> 2.6)
    public_suffix (4.0.7)
    racc (1.6.0)
    rainbow (3.1.1)
    rake (13.0.6)
    rb-fsevent (0.11.1)
    rb-inotify (0.10.1)
      ffi (~> 1.0)
    rexml (3.2.5)
    rouge (3.28.0)
    safe_yaml (1.0.5)
    sassc (2.4.0)
      ffi (~> 1.9)
    terminal-table (2.0.0)
      unicode-display_width (~> 1.1, >= 1.1.1)
    unicode-display_width (1.8.0)
    webrick (1.7.0)

PLATFORMS
  x86_64-linux

DEPENDENCIES
  http_parser.rb (~> 0.6.0)
  jekyll (~> 4.2.2)
  jekyll-feed (~> 0.12)
  jekyll-spaceship (~> 0.10.2)
  just-the-docs (~> 0.3)
  tzinfo (~> 1.2)
  tzinfo-data
  wdm (~> 0.1.1)
  webrick (~> 1.7)

BUNDLED WITH
   2.3.13