I hardly know where to begin. But here goes: there are now way too many options for a newbie like me to do what used to be relatively easy. (Is it a routine? An automation? A scene? Grrrr.)
First question: I created a virtual switch. It is authorized. But it is not showing up in ST app.
How come?
How did create the virtual switch? it is not showing in STHM or in the Device section of the app?
Below is an Edge driver for virtual devices that you should check out if you haven’t already:
I’m sure that’s very frustrating! (We often say SmartThings is very powerful, but not very intuitive. A lot of people, even advanced users, have to come to the forum to get help figuring out how to accomplish a particular task. So you’re definitely in the right place.)
First things first: you wrote “SHM,” the acronym for Smart Home Monitor, but that was a feature in the old app, circa 2017.
The similar security feature in the 2022 version of the app is STHM, the acronym for SmartThings Home Monitor. I just want to make sure we’re talking about the same thing and that you’re not trying to follow some out of date instructions. 
Second, why are you creating a virtual switch? It’s not needed for most features of STHM, but some people do use them to synchronize the location mode (when your phone is “home” or “away”) with the security mode (when STHM is disarmed or armed). But what were you specifically trying to accomplish, and were you following a specific post/article?
Third, how specifically did you create the virtual switch? There are currently three different primary methods:
A) use the virtual switch creator available in some android versions of the app
B) use the IDE to create a groovy virtual device. This is part of the old architecture.
C) use an Edge Driver (this is part of the new architecture and is now preferred over method B, because all groovy devices will stop working once the transition to the new architecture is complete, probably in a few months). This method does require that you have a ST hub, which the other two methods do not.
(There are also a few other really old methods using custom smartapps from about 5 years ago, but it’s not likely you used one of those.)
So…let’s get those 3 answers and then we’ll see if we can get you back on track. 
Did you look in Room Not Assigned for your virtual switch?
Thanks. STHM is correct. My mistake. I created the virtual switch(es) to work with Actiontiles. I used B to create.
Does a room need to be assigned? (This is probably more detail than anyone wanted, but I had this up and working fine for a few years, then changed modem/router which blew everything up and forced me to recreate much of this. 
)
No, it should work in no room assigned.