turned out to be a regex issue with the instagram plugin.. it was hardcoded to accept '10 chars' of the instagram slug, but some are 11 etc.. so that's why it was breaking.
$pattern = '#(http|https)://(|(.+?).)instagram.com/(?:p/)?((.+?){10})(|(\?|/)(.+?))#i';
to:
$pattern = '#(http|https)://(|(.+?).)instagram.com/(?:p/)?((.*))\/#i';
seemed to fix it..
pc!