I definitely observed my file losing data and was very careful about double checking before reporting it to you. However despite repeated attempts I have not been able to repeat the loss of data.
After failing to repeat the problem on a new file, my first reaction was that the failure to save only occurred with pre-existing files.
However in all subsequent attempts using File>Exit 'Yes' the files have saved correctly. And in all cases I still see the 'LeoQtLog.log.put fails' log message.
The lost data was plain body text. The files were not @file or @clean.
I was simply trying out using detached windows as discussed
earlierRegards
Lewis