Hi Littlejohnny89-
I'm Kevin B. Windows user like you. I do apologize for the inconvenience, let me help you sort things out.
If the Windows security is also not showing on your startup, kindly check if the Windows security services is running.
Press Windows key + R
Type: services.msc
Hit enter.
Look for Windows security services.
If it is not running, click on it then start.
After that right click on the services and click properties.
Change the startup type to automatic.
Click apply then okay.
If the services is already running try to restart it and set it to automatic.
Restart the computer and go to settings.
Click personalization.
Click taskbar.
Click select which icons appear on the taskbar.
Check if there is an option for Windows security notification icon.
Toggle it on then check if it will show on your system tray.
Please let me know what will happen. Hope this will help and have a blessed day!
Thanks,
Kevin B.
Independent Advisor