Shiny with flexdashboard not displayed properly

Question

I'm creating a shiny app using Rstudio and flexdashboard. When I use uiOutput twice in a section/column in does not display properly. There seem to be a large blank space between the output, and the second part of the output is hardly visible in the column/app. Any solution. Code example at screendump is linked below.

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

```{r}
library(rsconnect)
library(httr)
library(tidyverse)
library(flexdashboard)
```
### tester
```{r}
output$test <- renderUI({
  #cat("test5")
      str <- list(
      paste0("testing layout", collapse = " "),
      "\n")
    HTML(paste(str))
    })

htmlOutput("test")

output$test2 <- renderUI({
  #cat("test5")
      str <- list(
      paste0("Again testing layout", collapse = " "),
      "\n")
    HTML(paste(str))
    })

htmlOutput("test2")

```