Markers are not alligned with bars when a double horizontal axis is used

Plotly behaves strangely when two sets of data are superimposed, and there is a double horizontal axis.
Bars overlayed on bars give no issue: see the following reprex.

library(plotly)
#> Loading required package: ggplot2
#> 
#> Attaching package: 'plotly'
#> The following object is masked from 'package:ggplot2':
#> 
#>     last_plot
#> The following object is masked from 'package:stats':
#> 
#>     filter
#> The following object is masked from 'package:graphics':
#> 
#>     layout

plot_ly() %>%
  add_trace(x = ~1:31,
            y = ~1:31,
            name = 'blue data',
            type = 'bar') %>% 
  add_trace(x = ~101:131,
            y = ~31:1,
            opacity = 0.7,
            name = 'orange data',
            type = 'bar',
            xaxis = 'x2') %>% 
  layout(xaxis = list(title = ''),
         xaxis2 = list(
           overlaying = "x",                                        
           side = "top")
  )
#> Warning: `arrange_()` is deprecated as of dplyr 0.7.0.
#> Please use `arrange()` instead.
#> See vignette('programming') for more help
#> This warning is displayed once every 8 hours.
#> Call `lifecycle::last_warnings()` to see where this warning was generated.

^{Created on 2020-10-29 by the reprex package (v0.3.0)}

Now look at what happens if I replace the orange bars with orange markers: the second x axis on the top is squeezed between the second and the second to last bar, messing up the visualization.

library(plotly)
#> Loading required package: ggplot2
#> 
#> Attaching package: 'plotly'
#> The following object is masked from 'package:ggplot2':
#> 
#>     last_plot
#> The following object is masked from 'package:stats':
#> 
#>     filter
#> The following object is masked from 'package:graphics':
#> 
#>     layout

plot_ly() %>%
  add_trace(x = ~1:31,
            y = ~1:31,
            name = 'blue data',
            type = 'bar') %>% 
  add_trace(x = ~101:131,
            y = ~31:1,
            opacity = 0.7,
            name = 'orange data',
            type = 'scatter',
            mode = 'markers',
            xaxis = 'x2') %>% 
  layout(xaxis = list(title = ''),
         xaxis2 = list(
           overlaying = "x",                                        
           side = "top")
  )
#> Warning: `arrange_()` is deprecated as of dplyr 0.7.0.
#> Please use `arrange()` instead.
#> See vignette('programming') for more help
#> This warning is displayed once every 8 hours.
#> Call `lifecycle::last_warnings()` to see where this warning was generated.

^{Created on 2020-10-29 by the reprex package (v0.3.0)}

Start by running the two plot_ly() examples with add_trace() and layout(), comparing the bar and marker cases. Trace how the R plotting entry points handle overlaid xaxis and xaxis2 configurations; done means markers use the same horizontal alignment as bars without squeezing the top axis.