Disqus bugs: Count through identifier, javascript error on long pages

Hi I installed discuss and try to do simple things, however they do not work:

1) Comments count through identifier.
I use such code to display counts:
echo '<span class="disqus-comment-count" data-disqus-identifier="' . esc_attr(dsq_identifier_for_post($post)) . '">No Comments</span>';

It works weird. Sometimes works, sometimes not. Can show comments count for 50% of posts, can show nothing. If I try data-discuss-url – it works perfect, after this call next time I try identifier – it works, however after few more times stop working again.

I don’t want use URL because if I change post “slug” – then I can loose all my comments (URL changed).

2) In FIREFOX (latest version, Mac OS X El Capitan) on long scroll pages I get this error:
TypeError: b.body is null
embed.js (line 22, col 2619)

This happens because script is loaded in head part and body part is not fully loaded on long-scroll page when embed.js loaded.