Hoverlabel rgba not setting transparency

I’m plotting a px.choropleth_mapbox figure and, as the documentation states, the hoverlabel bgcolor property may be set as an rgb/rgba, but the alpha parameter apparently only changes the amount of white in the color, but the label remains opaque and I can’t see the plot behind. I found an answer for R that adding hovermode = 'x unified' should work, but it doesn’t for python in jupyter notebook.

rgba set to 'rgba(255,0,0,1)

rgba set to 'rgba(255,0,0,.2)