Problem with slashes in the url an single.php template

Hello! i have a problem with this plugin, for example:
I have a post with the next permalink:

my-site/lettuce/

Ok this work great even without plugin.
My problem come with another post about lettuces too which has the next permalink:

my-site/lettuce/how-eat/

With the last url, the post is saved with it, but when i can go to the single.php of that post, wordpress dont load the single.php template.

Any idea how to solve this?

i have tested this in twenty-fiften theme

Thank you for the support and for the plugin team ^^