R Plotly scatterplot color issues with multiple symbols

I’m having some strange trouble with scatter plot colors when I introduce symbols. As an example, the following “R” code correctly plots 20 data points with 20 different colors:

plot_ly(x=1:20,y=1:20,color=1:20,mode='markers')

However, if I now introduce two different symbol types, the scatter plot is reduced to 2 colors (however the hover text retains the 20 colors)

plot_ly(x=1:20,y=1:20,color=1:20,mode='markers',symbol=c(rep(0,10),rep(1,10)))

The result is here (sorry I can only post one image): http://imgur.com/AZaV7Tc

Is there an easy way to fix this?

I am having similar problems … and no idea what to do. Doesn’t seem to be much help via the forum.