I’ve had the same problem but fixed it with wpautop(). I had to run the data I got from the REST API through another function anyway and as I knew when to expect a return from a WYSIWYG field, I could return it with wpautop().
Like so:
function format_wysiwyg($value, $sType = 'default')
{
if ($sType === 'wysiwyg') :
return wpautop($value);
else :
return $Value;
endif;
}
I called it with format_wysiwyg($Value_from_rest, 'wysiwyg') if I knew it was WYSIWYG and just format_wysiwyg($Value_from_rest) if it wasn’t.
Not very smart, but it worked for my case.
