ABB SM500 Data Lost

I was notified by the office when an SM500 had a memory card full alarm. I stopped out the next day, copied the data off the card, then deleted the data files from the card, and put it back in the recorder. The SM500 went online, and successfully transferred its buffer to the card. I thought everything was fine, but I was wrong.

It turned out that a 3 day span of data (say from midnight on the 24th through midnight of the 27th) was gone. It wasn't on the card, and it wasn't in the data files I had copied over and sent to the office.

Any ideas of where it may have gone? I don't know how long the memory alarm had been active. There were around 267 files on the card when I began transferring the data. The specific timeframe makes me think that it could be a buffer issue, but I don't know.
I was asked to look into it. Was it a normal function, or an alarm. Is there an alarm history that could help bring understanding?

I've reached out to ABB, but figured someone here might know what happened.

update: I spoke at length with ABB tech support. The client had inadvertently failed to import all of the data files. The recorder had been configured to create a new file every day. This creates a ridiculous amount of small (1k-5k) files, when the recorder's default preference is to create 5MB files.

That was the main issue. The tech recommended a few configuration changes to optimize operation.