您好，我尝试根据您的UI代码进行操作，因为您没有提供足够的代码来重现该代码。这是我的代码，它工作正常。您可以根据需要进行更改。

library(shiny)
library(shinydashboard)
library(shinydashboardPlus)
library(DT)

ui <- dashboardPage(
  dashboardHeader(
    title = "Sales and Leads"),#sidebar content
  dashboardSidebar(
    sidebarMenu(
      menuItem("Breakdown by Day",tabName = "overview",icon = icon("dashboard")),menuItem("Breakdown by Month",tabName = "borders",icon = icon("th")),menuItem("Breakdown by Year",tabName = "sectors",icon = icon("th"))
    )
  ),#body content
  dashboardBody(
    tags$head(tags$style(HTML('
                              .content-wrapper,.main-body {
                              font-weight: normal;
                              font-size: 18px;
                              } '))),tabItems(

      #first tab content
      tabItem(tabName = "overview",fluidRow(
                infoBoxOutput("DialsYesterday"),infoBoxOutput("SalesYesterday"),infoBoxOutput("LeadsYesterday")
              )
      ),#second tab content
      tabItem(tabName = "borders",fluidRow(
                infoBoxOutput("DialsMonth"),infoBoxOutput("SalesMonth"),infoBoxOutput("LeadsMonth"))
      ),#third tab content
      tabItem(tabName = "sectors",fluidRow(
                infoBoxOutput("DialsYear"),infoBoxOutput("SalesYear"),infoBoxOutput("LeadsYear")
              ),fluidRow(
                  infoBoxOutput("DialsAll"),infoBoxOutput("SalesAll"),infoBoxOutput("LeadsAll")
              )

      )
    )
  )
)


server <- function(input,output,session) {

  output$DialsYesterday<-renderInfoBox({
    infoBox(" TAB 1 Title 1 DialsYesterday",value = 100,subtitle = "subtitile 1")
  })

  output$SalesYesterday<-renderInfoBox({
    infoBox("TAB 1 Title 2 SalesYesterday",subtitle = "subtitile 2")
  })

  output$LeadsYesterday<-renderInfoBox({
    infoBox("TAB 1 Title 3 LeadsYesterday",subtitle = "subtitile 3")
  })



  output$DialsMonth<-renderInfoBox({
    infoBox("TAB 2 Title 1 DialsMonth",subtitle = "subtitile 1")
  })

  output$SalesMonth<-renderInfoBox({
    infoBox("TAB 2 Title 2 SalesMonth",subtitle = "subtitile 2")
  })

  output$LeadsMonth<-renderInfoBox({
    infoBox("TAB 2 Title 3 LeadsMonth",subtitle = "subtitile 3")
  })


  output$DialsYear<-renderInfoBox({
    infoBox("TAB 3 Title 1 DialsYear",subtitle = "subtitile 1")
  })

  output$SalesYear<-renderInfoBox({
    infoBox("TAB 3 Title 2 SalesYear",subtitle = "subtitile 2")
  })

  output$LeadsYear<-renderInfoBox({
    infoBox("TAB 3 Title 3 LeadsYear",subtitle = "subtitile 3")
  })

  output$DialsAll<-renderInfoBox({
    infoBox("TAB 3 Title 3 DialsAll",subtitle = "subtitile 3")
  })

  output$LeadsAll<-renderInfoBox({
    infoBox("TAB 3 Title 3 LeadsAll",subtitle = "subtitile 3")
  })

  output$SalesAll<-renderInfoBox({
    infoBox("TAB 3 Title 3 SalesAll",subtitle = "subtitile 3")
  })




}



shinyApp(ui = ui,server = server)][1]][1]