This is a new QV12 feature that is widely documented in the community.
For various reasons (mostly performance-related) QV12 writes the live logs to a central directory C:\ProgramData\QlikTech\QlikViewBatch. Only when the script terminates (success or failure doesn't matter) will the logs be copied to their final destination(s).
You can even disable this behavior. See Rob's explanation here: Re: In Qlikview 12 SR7 , it does not generate logs during reloading of the qvw .