Hover issue in subplots when adding parallel coordinates

When using combined subplot the hover for "xy" and "polar" charts does not work when combining those types with a parallel coordinates chart. The "scene" chart type is not affected. If commenting the par. coord. and uncomenting the pie chart, it works...
Python 2.7, plotly 4.1.1.

from plotly.subplots import make_subplots
import plotly.graph_objects as go

fig = make_subplots(
    rows=2, cols=2,
    specs=[[{"type": "xy"}, {"type": "polar"}],
           [{"type": "domain"}, {"type": "scene"}]],
)

fig.add_trace(go.Bar(y=[2, 3, 1]),
              row=1, col=1)

fig.add_trace(go.Barpolar(theta=[0, 45, 90], r=[2, 3, 1]),
              row=1, col=2)

fig.add_trace(go.Parcoords(dimensions = list([ dict(label = 'x', values = [1,2,-1]),
                                               dict(label = 'y', values = [1,-2,1]),
                                               dict(label = 'f_1(x,y)', values = [-1,2,1]),
                                               dict(label = 'f_2(x,y)', values = [-1,-2,1])])
                          ),
              row=2, col=1)

#fig.add_trace(go.Pie(values=[2, 3, 1]),
#              row=2, col=1)

fig.add_trace(go.Scatter3d(x=[2, 3, 1], y=[0, 0, 0], z=[0.5, 1, 2], mode="lines"),
              row=2, col=2)

fig.update_layout(height=700, showlegend=False)

fig.show()

首先，使用指定的 Plotly 版本运行提供的 Python 复现，并比较包含和不包含 parallel coordinates trace 时 xy 和 polar 子图的 hover 行为。跟踪这些子图类型所使用的 hover 处理方式；当 xy 和 polar 图表与 parallel coordinates 结合时 hover 能正常工作，且不会导致 scene charts 回归时，即表示完成。