Specifically, I don't have Stardock Windowblinds. But then chno Start10 does not work as required that's for sure ! We are waiting for the developers to find this error and fix it. I think it needs to be given a CRITICAL STATUS, a very large number of people have two or more administrator accounts on their PC. It turns out that in the first one everything works and in all the others there is a glitch
I have performed a quick check here by creating a second admin account on my own computer. Start10 continues to be able to shut down the pc. Currently we have one user reporting this.
As I have stated before, the call to shutdown seems to be failing. Why it is failing I cannot say and I suspect the Windows 10 menu is using another api for shutdown / reboot as there are a couple of options.
Some questions :
1) When doing this are you physically on the machine in question (I.e. at the physically connected keyboard / mouse)? NOT via remote desktop or similar
2) Has this always been the case that shutdown / reboot is not working for you?
3) Does this happen if you instantly pick the option after login?