Perspective pane collapses rows when updating data

[rob-tay]

ALL software version info

panel 1.5.4
Windows, MacOS, Chrome, Edge

Description of expected behavior and the observed behavior

There appears to be a bug with the perspective pane automatically collapsing the hierarchy when the underlying data object is updated - this only seems to happen after clicking to expand or collapse a row. This makes it pretty annoying and difficult to use when a periodic callback is used to refresh the data.

I'd expect the depth of the hierarchy to be retained to whatever is currently visible.

Complete, minimal, self-contained example code that reproduces the issue

import pandas as pd
import numpy as np
import panel as pn
pn.extension('perspective')

def get_data(n=100):
    return pd.DataFrame({'x': np.random.choice(['A', 'B'], size=n), 'y': np.random.choice(['C', 'D'], size=n), 'z': np.random.normal(size=n)})

table = pn.pane.Perspective(get_data(), group_by=['x', 'y'], sizing_mode='stretch_both')

def update_data():
    table.object = get_data()

pn.state.add_periodic_callback(update_data)

pn.Row(table, sizing_mode='stretch_width', height=1000)

After collapsing "A", the rest of the levels will collapse and will get stuck