Chouby on "[Plugin: Polylang] Theme Menus Links (CPT Pages) shown for all languages"

Well I don't know WP-Ecommerce so I must admit that I am a bit lost.

What changed between 1.2.4 and 1.3 and which I think probably impacted you (because it was what I played around in 1.2dev57 too) is the 'parse_query' function in frontend/frontend.php:

if (isset($query->tax_query->queries))
	foreach ($query->tax_query->queries as $tax)
		if (pll_is_translated_taxonomy($tax['taxonomy']))
			$has_tax = true;

// allow filtering recent posts and secondary queries by the current language
// take care not to break queries for non visible post types such as nav_menu_items
// do not filter if lang is set to an empty value
// do not filter single page and translated taxonomies
if (/*$query->is_home &&*/ !empty($this->curlang) && !isset($qv['lang']) && !$has_tax && empty($qv['page_id']) && empty($qv['pagename']) && (empty($qv['post_type']) || $this->model->is_translated_post_type($qv['post_type'])))
	$query->set('lang', $this->curlang->slug);

has been moved to:

if (isset($query->tax_query->queries))
	foreach ($query->tax_query->queries as $tax)
		if ('post_format' != $tax['taxonomy'])
			$has_tax = true;

// allow filtering recent posts and secondary queries by the current language
// take care not to break queries for non visible post types such as nav_menu_items
// do not filter if lang is set to an empty value
// do not filter single page and translated taxonomies to avoid conflicts
if (!empty($this->curlang) && !isset($qv['lang']) && !$has_tax && empty($qv['page_id']) && empty($qv['pagename']) && (empty($qv['post_type']) || $this->model->is_translated_post_type($qv['post_type']))) {
	$this->choose_lang->set_lang_query_var($query, $this->curlang);
}

and to understand the new 'set_lang_query_var' function, this is how it is defined in frontend/choose-lang.php:

public function set_lang_query_var(&$query, $lang) {
	// backward compatibility WP < 3.5
	if (version_compare($GLOBALS['wp_version'], '3.5' , '<')) {
		$query->set('lang', $lang->slug);
	}
	else {
		// defining directly the tax_query (rather than setting 'lang' avoids transforming the query by WP)
		$query->query_vars['tax_query'][] = array(
			'taxonomy' => 'language',
			'field'    => 'term_taxonomy_id', // since WP 3.5
			'terms'    => $lang->term_taxonomy_id,
			'operator' => 'IN'
		);
	}
}

So as you can see, I now don't set anymore the language on single pages to avoid a conflict (I was aware of that but forgot it in 1.2.x)

Could you check that reverting this change does solve your issue?