Rmarkdown flexdashboard valueboxes do not render properly in Chrome or IE (but work in FireFox)

My flexdashboard works perfectly in firefox but in chrome or IE, the valueboxes don't render properly and they get hidden behind other page elements.

Showing in Firefox (on top) and Chrome/IE (on bottom):

Here is a reprex of my code:

title: "reprex"
runtime: shiny
    theme: yeti
    orientation: rows
    vertical_layout: scroll
    social: menu
    source: embed

$('.navbar-logo').wrap('<a href="http://www.website.com" target=blank>');

```{r setup, include=FALSE}
library(knitr) # for RMarkdown to HTML
library(rmarkdown) # to generate Rmd final document
library(shiny) # dashboard interactivity

Sidebar {.sidebar}
some text for the sidebar

some more text

Section 1

## Row 1 {data-height=9}

### valuebox1
valueBox("986070", icon = "fa-user-times")
### valuebox2
valueBox("8619681", icon = "fa-user-times")