hovermode='x unified' is causing unexpected behavior together with group_by()

library(tidyverse)
library(plotly)

TexasCities_plus_Houston <- ggplot2::txhousing %>% 
  group_by(city) %>%
  plot_ly(x = ~date, y = ~median) %>%
  add_lines(
    name = "Texan Cities", 
    text = ~paste0(city, "\n", median),
    hoverinfo = "text+x"
  ) %>%
  filter(city == "Houston") %>%
  add_lines(name = "Houston")

This works as expected (but the limitation is that it is hard to find Houston city to hover on):
TexasCities_plus_Houston %>% layout(hovermode = "closest")

This solves the above limitation, however, it does not matter which point you hover on, the same city name is shown ("Wichita Falls"). The "median" variable changes as expected, the problem seems to be solely with the variable used in group_by(), in this case, "city".
TexasCities_plus_Houston %>% layout(hovermode = "x unified")

Comienza ejecutando el reproductor de R proporcionado con plot_ly(), group_by(city), add_lines() y layout(hovermode = "x unified"). Compara las etiquetas de hover unificado con hovermode = "closest" y sigue cómo se selecciona el valor agrupado de city; se considera terminado cuando el hover unificado muestra la ciudad correspondiente al punto sobre el que se pasa el cursor y conserva la mediana cambiante.