shinyapps.io does not draw plots - r

Question

I built a simple app using FactorMineR package to do MCA analysis and clustering depending on selected variables.
The app works fine on my local device, however it does not show any plots (either base plots and ggplots) on shinyapps.io server. I checked the packages and locally and remotley they are the same. I also checked if the MCA() function from FactoMineR pcg even works by extracking some results and rendering them as a table what gave positive results. So there is only the problem with plots drawing. I have been trying to solve it for two days but nothing helps so I am asking you for any advice.
Here is how it looks locally:
Here is the link to the app: https://mikolajm.shinyapps.io/MCA_test/
And a reproducible example
library(shiny)
library(FactoMineR)
library(cluster)
library(ggplot2)
data(tea)
ui <- fluidPage(
# Application title
titlePanel("MCA"),
textOutput("packages"),br(),
tableOutput("table"),br(),
fluidRow(
column(4, checkboxGroupInput("Variables", "Select variables:",
names(tea), selected=c("breakfast", "tea.time"))),
column(4, plotOutput("plot")), column(4, plotOutput("plot1"))),
fluidRow(column(12, plotOutput("dendro", height = "700px", width="1200px"))
)
)
server <- function(input, output) {
## packages checking
output$packages <- renderText({.packages()})
tea_selected <- reactive({
tea[, input$Variables]
})
## table with some results from MCA() fun
output$table <- renderTable({
tea.mca <- MCA(tea_selected(), ncp=9)
tea.mca$eig[1:5,]
})
## mca1
output$plot <- renderPlot({
library(FactoMineR)
par(mfrow=c(2,2))
tea.mca <- MCA(tea_selected(), ncp=9)
})
## mca with ggplot
output$plot1 <- renderPlot({
tea.mca <- MCA(tea_selected(), ncp=9)
tea_vars_df <- data.frame(tea.mca$var$eta2, Variable =names(tea_selected()))
library(ggplot2)
pp <- ggplot(data=tea_vars_df, aes(x=Dim.1, y=Dim.2, label=Variable))+
geom_hline(yintercept = 0, colour = "gray70") +
geom_vline(xintercept = 0, colour = "gray70") +
geom_point()+
geom_text() +
ggtitle("MCA plot of variables ")+
theme_bw()
pp
})
### dendro
output$dendro <- renderPlot({
library(FactoMineR)
library(cluster)
tea.mca <- MCA(tea_selected(), ncp=9)
classif <- agnes(tea.mca$ind$coord,method="ward")
plot(classif,main="Dendrogram",ask=F,which.plots=2)
})
}
# Run the application
shinyApp(ui = ui, server = server)

Answer 1

EDIT: You can see plots obviously, but
ORIGINAL
I could not see plots in your shiny app when I ran your code.
After some digging, my guess is only that:
You use a lot of functions that come with the FactoMineR package. For instance, you use the function MCA in output$plot1 code block. Type MCA in your R command line, and it should print the function. You can see MCA does a lot of stuff and eventually calls plot.MCA. Now type plot.MCA in your R command line. You can see that plot.MCA has a lot of plot commands, and I'm pretty sure this executes all the plotting when you call MCA. I think your problem is that plot in the function plot.MCA is sent to the graphic device, and these plots are not saved, ie they are not return() to the parent environment. This is only speculation.