Issue with BIOS update in Windows 10

I tried to update the BIOS from our Latitude E5450 systems from A12 to A13 with a command line, distributed by our SCCM, but it does not install the BIOS, though I get a 'succeeded'  return message.

On shutdown and a boot later on, it still says 'A12'.
When trying to do a reboot aftwerwards, still no effect.

On immediate* reboot after the Install, it installs the 'A13' update.
(*immediately: being the first shutdown/reboot action after the BIOS installation)

I though it could be a Windows 10 'fastboot' issue so I disabled that option, but still, when choosing 'shut down' after the succesfull BIOS update, it does not update the BIOS on the next boot.

The command line I use is:
A13.exe /s /f /p=xxxxx /l="C:\Temp\BIOS.txt" /forceit

The bios.txt logfile says:

***BIOS flash started on 7/5/2016 at 16:41:46***
Command: \\xxxxxxxxxxxxxx\A13.exe /s /f /p= /l="C:\temp\bios.txt" /forceit

A12 INSTALLED (Dell System Latitude E5450)
- Gigabit Ethernet : X01
- System BIOS with BIOS Guard : A12
- Embedded Controller : A06
- Intel Management Engine (VPro) Update : 10.0.47.1006

A13 UPDATE (Dell System Latitude E5450)
- System BIOS with BIOS Guard : A13
- Embedded Controller : A06
- Gigabit Ethernet : X01
- Legacy Video OROM : 1039.V.18
- Legacy N15SGM OROM : 82.8.18.42
- Legacy N15SGT OROM : 82.8.18.43
- Legacy RAID OROM : 13.2.2.2224
- Intel Management Engine (VPro) Update : 10.0.47.1006
- Intel Management Engine (Non-VPro) Update : 10.0.47.1006
- Intel AntiTheft : 3.0.0.18

Exit Code = 2 (Reboot Required)
***BIOS flash finished at 7/5/2016 at 16:41:56***

But, once again,
shutdown and a boot later on -even without fastboot- = no update is installed
immediate restart = update is installed

I do not recall having had this problem on Windows 7. There I could force the BIOS to update and let the user shut down the computer when he/she wanted - and it would Install on the next boot.

Is this a new Windows 10 issue?
How do you propose to update the BIOS over the network on remote locations?