There are several things you need to check in your Unraid setup to help prevent the dreaded unclean shutdown. There are several timers that you need to adjust for your specific needs.
There is a timer in the Settings->VM Manager->VM Shutdown time-out that needs to be set to a high enough value to allow your VMs time to completely shutdown. Switch to the Advanced View to see the timer. Windows 10 VMs will sometimes have an update that requires a shutdown to perform. These can take quite a while and the default setting of 60 seconds in the VM Manager is not long enough. If the VM Manager timer setting is exceeded on a shutdown, your VMs will be forced to shutdown. This is just like pulling the plug on a PC. I recommend setting this value to 300 seconds (5 minutes) in order to insure your Windows 10 VMs have time to completely shutdown.
The other timer used for shutdowns is in the Settings->Disk Settings->Shutdown time-out. This is the overall shutdown timer and when this timer is exceeded, an unclean shutdown could occur. This timer has to be more than the VM shutdown timer. I recommend setting it to 420 seconds (7 minutes) to give the system time to completely shut down all VMs, Dockers, and plugins.
These timer settings do not extend the normal overall shutdown time, they just allow Unraid the time needed to do a graceful shutdown and prevent the unclean shutdown.
One of the most common reasons for an unclean shutdown is having a terminal session open. Unraid will not force them to shut down, but instead waits for them to be terminated while the shutdown timer is running. After the overall shutdown timer runs out, the server is forced to shutdown. If you have the Tips and Tweaks plugin installed, you can specify that any bash or ssh sessions be terminated so Unraid can be gracefully shutdown and won't hang waiting for them to terminate (which they won't without human intervention).
If you server seems hung and nothing responds, try a quick press of the power button. This will initiate a shutdown that will attempt a graceful shutdown of the server. If you have to hold the power button to do a hard power off, you will get an unclean shutdown.
If an unclean shutdown does occur because the overall "Shutdown time-out" was exceeded, Unraid will attempt to write diagnostics to the /log/ folder on the flash drive. When you ask for help with an unclean shutdown, post the /log/diagnostics.zip file. There is information in the log that shows why the unclean shutdown occurred.