From the SO question, try this without the div:
fluidPage(
shinyjs::useShinyjs(),
id = "input-panel",
tableUI("opfun"),
numericInput("budget_input", "Total Forecast", value = 2),
actionButton("opt_run", "Run"),
actionButton("opt_reset", "Reset")
)
I can't test because you did not provide a reprex. See Shiny debugging and reprex guide