Question - do you not SEE the script run, or does it not map the drives?
I deployed a Windows 8.1 Pro workstation this weekend and our login script runs as always. I did set the DelayedDesktopSwitchTimeout value on the workstation to Zero, though.. our script runs fast - 4-5 seconds - and the timeout of 30 seconds was both annoyingly slow and blocked the login script from running visibly during login.
We're running Kix 4.62 - I can verify 4.63 tonight.
The boot time is generally not an issue - things happen in a specific sequence.. BUT!!!
It's possible that you are not defining the Wait for Network at Startup setting in GPO.
This delays the presentation of the login screen until the workstation can see AD when connected to a domain network. With the setting disabled, the computer can log you in with cached credentials, and login scripts and GPOs will not run at that time. The net effect of enabling this setting is a few second delay between BOOT and the display of the C-A-D login screen. This issue is usually only seen after a computer cold boot because the login can be made available before all networking is initialized. A cold boot will fail but a logoff/logon will usually work properly if this setting is not defined and the cause of the problem.
Glenn
_________________________
Actually I
am a Rocket Scientist!
