For me, malware realtime protection was turned off after a clean installation. I turned it on, it was stuck at starting. I then rebooted and now everything is turned on. Seems like a visual glitch where the button does not move from starting to "on". Can not say anything if the alert message will come back as i just reinstalled everything on my machine.
For me, malware realtime protection was off on a perfectly clean windows 10 installation. I enabled it and it was also stuck at starting. I waited a few minutes and restarted my PC. Every since then, it is set as "on" and everything seems to be working fine. Looks more like a visual glitch where the button does not move from "starting" to "on"