Not all tooltips on multi-layer ribbon plot are displayed

[IKupriyanov-HORIS]

Plot:

from lets_plot import *
LetsPlot.setup_html()

a = {
    'g': ['a', 'a', 'a', 'a'],
    't': [300, 370, 345, 310],
    'b': [250, 200, 270, 250],
    'x': [100, 105, 110, 115]
}

b = {
    'g': ['b', 'b', 'b', 'b'],
    't': [405, 425, 400, 300],
    'b': [100, 300, 150, 200],
    'x': [100, 105, 110, 115]
}

p = {
    'x': [100, 102, 105, 107, 110, 112, 115],
    'y': [560, 500, 550, 445, 555, 525, 535],
    'g': ['A', 'B', 'C', 'D', 'E', 'G', 'H']
}

ggplot() \
    + geom_ribbon(aes(x='x', ymin='b', ymax='t'), fill='red', alpha=0.6, data=a) \
    + geom_ribbon(aes(x='x', ymin='b', ymax='t'), fill='orange', alpha=0.6, data=b) \
    + geom_point(aes(x='x', y='y', color='g'), data=p)

Expected:
Tooltip for the point C when the cursor position is (105, 550).
Tooltip for the red ribbon when the cursor position is (105, 200).

Actual:
Image is the same for both cases: