Classes on images not working

Putting a class on an image using markdown syntax as outlined in the Grav docs does not seem to be working.

I'm using this syntax:

![Some ALT text](sample-image.jpg "My title") {.myclass}

I tried doing this in the system.yaml. Actually I turned them on in the admin dashboard but verified the config set is in the yaml file.

  process:
    markdown: true
    twig: true
  twig_first: true

you would need:

markdown:
   extra: true

As that style of declaration is actually not standard markdown, but markdown-extra: https://michelf.ca/projects/php-markdown/extra/#spe-attr

However, you can do it totally native, with no twig required like this:

![Some ALT text](sample-image.jpg?classes=myclass)

That's built in to Grav (see these docs)

Aha! Thank you! - Also, I'm wondering if this problem could be more simply solved with shortcodes? When I'm not exhausted I'll read about those plugins.