Under panel 1.2.1, setting .visible to True for a widget that is initially created with visible=False doesn't toggle its visiblity

[giftculture]

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ALL software version info

Panel v1.2.1

Description of expected behavior and the observed behavior

When creating a widget with visible=False, setting .visible to True doesn't reveal the widget. The below code works under panel v 1.2.0 as expected - it reveals the spinner, sleeps for 5 seconds, and then hides the spinner. Looking at the javascript console when the script is executed under panel v1.2.0, the css style ":host { display: none !important; }" is applied at the start, is removed when I click the submit button and .visible is set to true, and then added back once .visible is set to false

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

import panel as pn
import logging
import bokeh
import time
logger = logging.getLogger('panel.tifviewer')
pn.extension(sizing_mode='stretch_width') #stretch_width


pn.__version__

load_and_display_spinner = pn.indicators.LoadingSpinner(value=False, height=100, width=100, visible=False)                      
submit = pn.widgets.Button(name='submit', button_type='primary')
main_ui = pn.Column(
                pn.Row(
                    pn.pane.Markdown(f'## my panel version is {pn.__version__}'),
                ),
                pn.Row(
                    submit
                ),
                pn.Row(
                    load_and_display_spinner
                ),
              
          ) 

tabs = pn.Tabs(
    ('app', main_ui),
).servable()
    

def load_display(spinner, x):
    print(f"spinner is {spinner}")
    print(f'switch is {x}')
    if (x == 'on'):
        spinner.value = True
        spinner.visible = True
    if (x == 'off'):
        spinner.value = False
        spinner.visible = False

def do_some_task(event):
    load_display(load_and_display_spinner, 'on')
    time.sleep(5)
    load_display(load_and_display_spinner, 'off')
                

submit.on_click(do_some_task)

Stack traceback and/or browser JavaScript console output

Screenshots or screencasts of the bug in action

[ahuang11]

import panel as pn

pn.extension(sizing_mode="stretch_width")  # stretch_width

def toggle_visible(event):
    ls.visible = not ls.visible

ls = pn.widgets.LoadingSpinner(visible=False, value=True)
bt = pn.widgets.Button(name="Click me", button_type="primary")
bt.on_click(toggle_visible)

pn.Column(ls, bt).servable()

So if ls.visible = True initially, it works, but not if initialized with ls.visible = False

I think the reason is visibility: hidden doesn't get dropped

[emcd]

I see a fix for this was slated for the v1.2.2 milestone and v1.2.2 was released yesterday. Is this going to be retargeted for v1.2.3? This is a fairly high visibility bug, if you'll pardon the pun.