Variable in scope is not visible after a bang!-operation in CE

[Repro.zip](https://github.com/dotnet/fsharp/files/8898420/Repro.zip)

At least in the async CE, after a monadic operation (let!/do!/match! etc.), variables in the debugger suddenly seem to go out of scope:

```f#
module Program =

let f x =
async {
do! async.Return ()
return 1
}

[]
let main _argv =
f 0 |> Async.RunSynchronously |> printfn "%A"
0
```



(Screenshots from Rider. Originally [reported there](https://youtrack.jetbrains.com/issue/RIDER-78577), but was redirected here.)