Probably because this complex command is doing a listPrint in it and you are getting the entire output on stdout.
This does not create a result object to be saved,
Look at the complex command definition for this command
LogItem getLogItemsByJobRun <job run key> <job run id >
this returns a list of log items for this job run.
store this item, this is the list item you can use,
What do you want to with this log ?