xAPI occasionally not sending PASSED and also showing strange duration

We have an xAPI course that is triggered to send "completed/passed" statements upon reaching a certain slide in the course, as well as a "completed" statement for 90% of slides viewed.  For some learners, the LRS is not receiving "passed," but only "completed," which would be fine, but the LRS is not reading them as having progressed through the course even though they have "experienced" all the required slides, and the data tables indicate the learner spent 200 days in the course, even though the course has only been available for a few days.

Has anyone experienced this anomaly?  Most of the learners are receiving proper data.