I was driving for about five hours yesterday and listening to the Audio version of the Modile Ed course NT221.
I hadn't downloaded the audio tracks to my iPhone and so they were streaming over the cellular network. Mostly it worked fine but there were occasions when I had poor network signal and poor / no data connection.
If this happened when I reached the end of a segment sometimes the app skipped a section and marked sections as done incorrectly.
The screenshot below demonstrates this:

I had listened to "Jesus' Encounter with the Samaritan Woman, Part 1" but not part 2.
Neither had I listened to the segment "Jesus' Second Sign' even though it is marked as Done
It picked up again in "Jesus Heals on the Sabbath".
Any thoughts as to why this might happen?