Categoryorder not working when specifying plot type

When using the category order parameter, no plot is generated if the plot type is specified in the plot_ly call:

p <- plotly::plot_ly(type = 'bar')
colNames <- names(iris)
colNames <- colNames[-which(colNames == 'Species')]

for(trace in colNames){
  p <- p %>% plotly::add_trace(data= iris, x = ~ Species, y = as.formula(paste0("~`", trace, "`")), name = trace)
}

p  %>% layout(xaxis = list(categoryorder='total descending'))

With the following warning, which I don't understand since I'm not combining discrete and non-discrete data in the same axis:

Warning message:
Can't display both discrete & non-discrete data on same axis 

If I specify the type in add_trace instead of the plot, then it works correctly and the warning is gone:

p <- plotly::plot_ly()
colNames <- names(df)
colNames <- colNames[-which(colNames == 'Species')]

for(trace in colNames){
  p <- p %>% plotly::add_trace(type = 'bar', data= iris, x = ~ Species, y = as.formula(paste0("~`", trace, "`")), name = trace)
}

p %>% layout(xaxis = list(categoryorder='total descending'))

Maybe this is the intended behavior? If so, why does specifying the type in the traces works and not in the plot? The warning seems unclear to me.

Beginne damit, die bereitgestellte R-Reproduktion mit iris auszuführen, und vergleiche plot_ly(type = 'bar') mit add_trace(type = 'bar'). Verfolge, wie plot_ly und add_trace den type weitergeben und wie layout(xaxis = list(categoryorder = 'total descending')) mit den daraus resultierenden Traces umgeht. Als erledigt gilt die Aufgabe, wenn die Reproduktion keine Warnung mehr ausgibt und die Kategorie-Reihenfolge konsistent funktioniert.