Logfile erased after extraction datalogger.

Hi,

I updated to b81 yesterday.
For some reason my laptop was turned off.(Nothing to do with the update!)
Now I am missing 3 hours of data tonight.
I extracted the datalogger for the time missing.(Action/Extract from datalogger/“setting time”)
Now my logfile only holds those 3 last hours, the rest has been erased.
I have done this a ton of times and Always succeeded.
Was there a setting unticked or something by the update.

And most important, how can I get my logfile of September completely back.

TIA

The logfile has been retrieved.

Should I tick the option Append when I want data extracted added to the end of the logfile.
Now it is creating a new logfile.
I can’t remember this was set on my b79 versions or earlier versions.