Problem is showing confidence intervals using stat_summary and ggplot

[asorribas]

I'm using the following code in learnr:

ggplot(PlantGrowth,aes(group,weight,color=group))+
  stat_summary(fun.data=mean_cl_normal,size=1)

It works ok BUT when I upload the learnr document to an account in shinyapps.io the generated app doesn't show the plot with the confidence interval (in fact only the axes are shown)

All the other computations work fine (tables, ANOVA, etc...)
Any suggestion?