Why do checkboxes not appear when the page loads?

Checkboxes may not be visible on page load for several reasons:

• HTML markup error: for example, missing <input type="checkbox"> tag or incorrect nesting.
• CSS styles hiding checkboxes: display: none;, visibility: hidden;, opacity: 0;, or checkboxes are overlapped by other elements.
• JavaScript errors: scripts that should create or display checkboxes are not executing or throw exceptions.
• Asynchronous data loading: if checkboxes depend on data that hasn't loaded or loaded with an error.

To diagnose, check:

• Browser console for errors.
• HTML code via developer tools.
• Styles applied to checkboxes.
• Loading and rendering logic in JavaScript.