CheckButtonGroup does not hold the value

I am trying to create my first app and I have code below. However the CheckButtonGroup does not hold values. If I click on ‘Strawberry’ in first CheckButtonGroup and ‘Pear’ in second CheckButtonGroup, the ‘Strawberry’ in first one is un-clicked again. However the value of view.coarse1 is still correct. Can you please help me, am I missing something?

import panel as pn
import param
import holoviews as hv
class WoeViewer(param.Parameterized):
    options=['Apple', 'Banana', 'Pear', 'Strawberry']
    coarse1 = param.ListSelector( objects=options)
    coarse2 = param.ListSelector( objects=options)
    @param.depends('coarse1','coarse2', watch=True)
    def _update_coarse(self):
        self.param['coarse2'].objects = [option for option in self.options if option not in self.coarse1] 
        self.param['coarse1'].objects = [option for option in self.options if option not in self.coarse2]
view = WoeViewer(name='WOE Viewer')

full=pn.Param(view.param, widgets={
    'coarse1': pn.widgets.CheckButtonGroup,
    'coarse2': pn.widgets.CheckButtonGroup