Thanks for your bug report.

The most common reason for this issue is anti-virus software that is blocking further writing to the file while it scans the file.

I just tested your script with v7.76 on a 5400rpm drive and it worked fine here.

I also tested v7.45 and v7.46 and they both worked fine as well. There is no difference in the /write source code between v7.45 and v7.46.