Shiny, flexdashboard and databases issue: app only functions once

My brain hurts:

I've built a simple flexdashboard that fetches data from a database.
It runs fine the first time. When I run the app again the data is no longer fetched.
I can then change the name of a variable in the document, save it, and then it runs fine again ...
but only the first time.

I simply do not understand what is going on under the flexdashboard hood and would appreciate any insights.
I fear that there is some important house keeping that I fail to do.

I run:

R version 3.4.3 (2017-11-30)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 16.04.3 LTS

other attached packages:
[1] pool_0.1.4 dplyr_0.7.4 purrr_0.2.4 readr_1.1.1 tidyr_0.7.1 tibble_1.4.2
[7] ggplot2_2.2.1.9000 tidyverse_1.1.1 flexdashboard_0.5.1

shiny-server - Shiny Server v1.5.6.875 (Node.js v6.10.3)

Below is a minimal example that replicates the issue on my machine.

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

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

	```{r}
	con <- dbPool(
	  drv = RMySQL::MySQL(),
	  dbname = "shinydemo",
	  host = "shiny-demo.csa7qlmguqrf.us-east-1.rds.amazonaws.com",
	  username = "guest",
	  password = "guest"
	  )
	```

	```{r}
	tbl_gps <- reactive({

	  dplyr::tbl(con, dplyr::sql("SELECT * FROM City")) %>% 
		dplyr::collect()
	  
	})
	```

	Column {.tabset .tabset-fade}
	-----------------------------------------------------------------------

	### Table

	```{r dice}
	DT::dataTableOutput("sliced")
	output$sliced <- DT::renderDataTable(tbl_gps(), filter = c("bottom"))
	```

I don't think the app is recognising the runtime: shiny part of the yaml because it is indented. try un-indenting so that it sits in-line with the title and output parts

That did it!

You are a super hero - what a stupid error - I could have spend forever looking in all the wrong places to figure out what was happening!

Thanks!

Glad to hear you're up and running. Could you please mark the solution to your question?