Hyperdeck Mini missing end of recording, creates mcc

I record the same meeting, in the same manner, three times a month. It's usually 5 or 6 hours and has several stops and starts. Now the third time in the past dozen meetings the last file created is missing the last couple of minutes. It's always the last recording of the day (we stop recording at the breaks). Each time this happens it also creates an empty .mcc file. What could be going on?
Obviously, the client does not find this acceptable. Last week I bought another Hyperdeck. The same thing happened.
Obviously, the client does not find this acceptable. Last week I bought another Hyperdeck. The same thing happened.