Moodle provides the option to configure the default blocks to be displayed on user dashboards (the "/my" page).

Some users report that when adding blocks to the default dashboard, images within the blocks aren't displayed on the dashboard page when a user logs in. That is to say - the images only show up when editing the default dashboard page, but not on the actual user dashboard page.

The fix for this is simple. It's actually rooted in how Moodle manages contexts and block appearance settings.

When editing the block on the default dashboard page, be sure to select "Any page that matches the one above" under the block's "Where this block appears" section.

This will ensure that all images and contents within the block are displayed universally across all user dashboard pages, as intended.