Async macro WYSIWYG:By default, the async block is invisible in the editor

Charpentier Lucas I don't see any difference between the {{async}} macro and any other macro relying on async rendering when it comes to the WYSIWYG editor. In both cases:

• inplace editor: the macro output is initially invisible until the editing area is first focused; the macro placeholder is visible afterwards; this is XWIKI-19833
• standalone: the macro placeholder is initially visible

For both editors, the output of the async macro is visible once we switch to Source and back or insert another macro.