showTab not displaying contents properly with bslib

[philstraforelli]

Describe the problem

I'm running into an issue where bslib is not displaying the contents of a tab with showTab() when "base" shiny is working fine.

Here's an example of a "base" shiny that works as desired:

library(shiny)
library(bslib)

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      checkboxGroupInput("create_tabs", label = "Select an option to create a tab",
                         choices = c("Letters", "Numbers", "Symbols")),
      tabsetPanel(id = "Options",
                  tabPanel("Letters", checkboxGroupInput("Letter_options", label = "Letter options",
                                                         choices = LETTERS[1:5])),
                  tabPanel("Numbers", checkboxGroupInput("Number_options", label = "Number options",
                                                         choices = 1:5)),
                  tabPanel("Symbols", checkboxGroupInput("Symbol_options", label = "Symbol options",
                                                         choices = c("$", "#", "&", "!", "?")))
      )
    ),
    mainPanel()
  )
)

server <- function(input, output, session) {
  observe({
    if ("Letters" %in% input$create_tabs) {
      showTab("Options", target = "Letters", select = TRUE)
    } else {
      hideTab("Options", target = "Letters")  
    }
    
    if ("Numbers" %in% input$create_tabs) {
      showTab("Options", target = "Numbers", select = TRUE)
    } else {
      hideTab("Options", target = "Numbers")  
    }
    
    if ("Symbols" %in% input$create_tabs) {
      showTab("Options", target = "Symbols", select = TRUE)
    } else {
      hideTab("Options", target = "Symbols")  
    }
  })
}

shinyApp(ui, server)

See this gif of the app working as desired: https://i.imgur.com/qJMMtwb.mp4

However, if I implement bslib using the following code:

ui <- page_sidebar(
  sidebar = sidebar(
    checkboxGroupInput("create_tabs", label = "Select an option to create a tab",
                       choices = c("Letters", "Numbers", "Symbols")),
    tabsetPanel(id = "Options",
                tabPanel("Letters", checkboxGroupInput("Letter_options", label = "Letter options",
                                                       choices = LETTERS[1:5])),
                tabPanel("Numbers", checkboxGroupInput("Number_options", label = "Number options",
                                                       choices = 1:5)),
                tabPanel("Symbols", checkboxGroupInput("Symbol_options", label = "Symbol options",
                                                       choices = c("$", "#", "&", "!", "?")))
    )
  ),
  card()
)

Now when I select a tab to open, the contents do not show: https://i.imgur.com/R74cENE.gif

Session Info

version  R version 4.5.2 (2025-10-31 ucrt)
 os       Windows 11 x64 (build 26200)
 system   x86_64, mingw32
 ui       RStudio
 language (EN)
package     * version    date (UTC) lib source
 bslib       * 0.9.0.9002 2025-11-21 [1] Github (rstudio/bslib@0757592)
shiny       * 1.11.1     2025-07-03 [1] CRAN (R 4.5.2)