I'm not yet running any Windows 10 in our environment so cannot properly test. Home user machines might be close enough but not sure. Also one thing to consider is that every single OS Microsoft has made has more hand holding and monitoring to make sure you the user or automated tasks are not doing something they should not be doing. I'm not saying that is the case here but it very well could be. You can trying running process explorer on it and see if it can track down a specific issue or not but in the long run a 2 second login script that is hidden in the first place really is not that long.