Long event recorded only in 10-second fragments on "Optimal Surveillance"

Hi! I just had a conversation with someone on my front door. I was hoping that it would be recorded in its entirety, but all I found in the recordings are a handful of 10-second fragments.
This is odd, because I have the camera set on “Optimal Surveillance” working mode, which should record fragments up to 60 seconds.
Is this a defect, @AnkerSupport?

While you have it set to optimal recording, if no movement is seen or it stops, it could have just reverted to the 10 second recording.