Issue Magento 1.9.x: Pagination in reverse

[v_alex]

We have an ecommerce in Magento 1.9.x and a problem for categories between 11 and 31 products.

When the categories has between 11 and 20 products, show this errorError for categories with 11 and 20 products

And when the categories has between 21 and 30 products, show this errorError for products with 21 and 30 products

For categories with more than 30 products, the pagination back to normal.

The expected result

Anyone has experience with a bug like this? Where we can fix it?

Link for an example:
http://casamusa.enexum.cl/ejemplo.html

Now, we tried to reload the toolbar.phtml original from github but nothing happens, thanks for help.

[theMageComp]

Waiting for the image to be approved.
Or can you upload and send the link of images?

[v_alex]

Yes, of course, there is the links.

[1]: https://i.stack.imgur.com/lncM6.png
[2]: https://i.stack.imgur.com/NyNNK.png
[3]: https://i.stack.imgur.com/iE2Ma.png