Not having any of your code available, it is not entirely clear why your cms block is not working.
As per my comments on your question, it is very likely that you need to set the block as allowed to display.
Refer here:
Product list by category in CMS page
However, consider to not use a custom block and filters to display what you need. Use a category.
Assign all the noted products to a new category. Then use the core blocks to display that in your page:
{{block type="catalog/product_list" category_id="12" template="catalog/product/list.phtml"}}
No need to go create any new code/modules and you can set a different template to handle the display of this list (if needed to display different to your usual product category lists)
You may also be interested in this: http://www.proxiblue.com.au/blog/smarter-cms-category-product-limits/
You can also automate the category by using a tool such as this - http://www.proxiblue.com.au/premium-modules/magento-dynamic-category-products.html (yes some blatant self promotion)
simply set the rules, and forget about it. Your sales category will stay updated automatically, daily. No need to manually manage your category products going forward.