Simple Pagination

I have the following simple pagination at the bottom of each of my custom posts and the functionality does not work as expected. The previous post does not start out correctly and when I get to the last post the previous post and the next post become the same.

<li class="prev-link"><?php previous_post_link('%link', '<i class="fa fa-chevron-left"></i> Previous: %title'); ?> </li>
                    <li class="next-link"><?php next_post_link('%link', '%title :Next <i class="fa fa-chevron-right"></i>'); ?> </li>

Any ideas why it’s doing this?

K.

https://ww.wp.xz.cn/plugins/post-types-order/