I've created fields on a collection type called projects that are used to assign different sort values based on category. In order to create previous/next links that use that assigned order, I've used the collection:previous and collection:next tags. The next link works as expected, but the previous doesn't. I've posted the tags for the general category (which uses the general_sort field to establish the order of the projects). Am I missing something?

<a class="work-prev work-nav-icon" href="{{ collection:previous in='project' sort=general_sort general_sort:isnt='' show_unpublished='false' as='posts' wrap='true' limit='1' }}{{ posts }}{{ site_url }}project/{{ client | slugify }}/{{ project_title | slugify }}{{ /posts }}{{ /collection:previous }}?cat=general">
      {{ partial:work_nav_prev }}
</a>
<a class="work-next work-nav-icon" href="{{ collection:next in='project' sort='general_sort' general_sort:isnt='' show_unpublished='false' as='posts' wrap='true' limit='1' }}{{ posts }}{{ site_url }}project/{{ client | slugify }}/{{ project_title | slugify }}{{ /posts }}{{ /collection:next }}?cat=general">
      {{ partial:work_nav_next }}
</a>