MultiChoice placeholder doesn't appear

I’m trying to set a placeholder for a MultiChoice widget but it doesn’t appear.

Bokeh version: 2.2.3
OS: WSL
Example:

from bokeh.io.doc import curdoc
from bokeh.models import MultiChoice

mc = MultiChoice(
    placeholder='Choose label',
    options=['My Label'],
    title='Label(s)',
)

curdoc().add_root(mc)

@roinr This is a known, still open issue:

I see…thanks