Tin Can courses not removing bookmark / state data

We have a number of articulate courses in our custom LMS which are published for the Tin Can API. To support these courses, we have an instance of Learning Locker LRS. Everything has been working great for a few months, but due to usage, we are now experiencing issues due to the number of documents that have been sent to Learning Locker via the State API (for bookmarking). Since each of these requests results in the storage of a file on the server, our server is overwhelmed by the number of files (not size, just number; over 3 million). 

As noted below, the Activity Provider (the Articulate course) is responsible for deleting these documents when they are no longer required. However, it does not appear to us that Articulate is doing anything to remove these files.

Is there a feature/option within Articulate that we are missing or anything we can look for as a reason why these older files are not being deleted? 

Per https://tincanapi.com/deep-dive-state-activity/

The State API
Within the State API Documents can be stored on two different levels. First, data can be stored on a per user, per activity basis. Common uses include high scores or bookmarking data. Next, data can be on a per registration, per user, per activity basis. This is used for data specific to a particular launch or attempt. The Activity Provider is responsible for cleaning up after itself and deleting old state documents which are no longer required.