Switch user was a special kind of lock and unfortunately Microsoft have made the OS automatically dismiss the lock screen when you do not have a password.
We will be investigating other solutions to this, but for now using a password is a workaround. Note that the use of a password is always recommended anyway.
Thanks for the reply
Currently opening the standard 10 menu with Ctrl and switching user by clicking the user icon is working for me
Hitting win + L takes you directly to the lock screen too, maybe you could just make switch user do that?