Gonna jump in here and mention I *may* be experiencing this issue as well. If not the same issue, then a very similar one.
My issue can be easily replicated in the admin screen with the edit.php columns. Clicking on the CPT-onomy name within the those columns will filter the post_type appropriately, but for some CPT-onomies will return no posts, or even not all of the posts (returning 1 post when it should return 2).
For me the solution seems to be updating the slug to an ID. The ID always returns the correct posts, while the slug can suffer from the above irregularity.
Here’s some screenshots that might help my explanation:
https://chipmunkbay.com/junk/ex1.gif
https://chipmunkbay.com/junk/ex2.gif
https://chipmunkbay.com/junk/ex3.gif
Bear in mind that my site is still in development and only has about 10 posts for testing, so perhaps the ID method could still return incorrectly similar to the slug method, given a larger pool of posts.
Oh, and I’m using plugin ver 1.3.4 as well.
Hope this helps.
