Flexdashboard doesn't work with Shiny URL state.

I am trying to combine flexdashboard with Shiny state bookmarking. When used alone (example from the docs) Shiny app works fine, but when put in flexdasboard, url is not updated:

---
title: "Untitled"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
    runtime: shiny
---

```{r setup, include=FALSE}
library(flexdashboard)
```

Column {data-width=650}
-----------------------------------------------------------------------

### Chart A

```{r}

shinyApp(
  ui=function(req) {
    fluidPage(
      textInput("txt", "Text"),
      checkboxInput("chk", "Checkbox")
    )
  },
  server=function(input, output, session) {
    observe({
      # Trigger this observer every time an input changes
      reactiveValuesToList(input)
      session$doBookmark()
    })
    onBookmarked(function(url) {
      updateQueryString(url)
    })
  },
  enableBookmarking = "url")
```

Is this even possible?

Start with the embedded flexdashboard/Shiny example and compare it with the standalone Shiny URL-state bookmarking example referenced in the issue. Trace the URL update path when inputs change and document a reproducible test; it is done when the dashboard updates the URL consistently with the standalone app.