Hi Eduard,
We are using the WordPress Default editor.
Also we are noticing sometimes the FV player shortcode when added via our ACF WYSIWYG it will show up in our main body.
Also is there anyway to turn off the video adding its own dimensions to the player? I have a default set but it continues to add itself to the main body 40% of the time.
Kind of resolved.
If the wysiwyg is in code window, it will not work, but in visual display it will work. Not ideal but works.