FileSelector not working inside Template

Panel
1

I can not seem to make File Selector work as part of a template.

import panel as pn # 1.8.2

pn.extension()

class FileSelectorDebug(pn.viewable.Viewer):
    def __init__(self, **params):
        super().__init__(**params)
        self.file_selector = pn.widgets.FileSelector(
            name="Select files",
            directory="~",
        )
    
    def __panel__(self):
        # This works
        return self.file_selector

        # This results in a frozen Widget (can not interact with it)
        # return pn.template.MaterialTemplate(
        #     header_background="#FFA500",
        #     logo="https://www.canada.ca/etc/designs/canada/wet-boew/assets/sig-blk-en.svg",
        #     site="File Selector Debug",
        #     title="File Selector Debug",
        #     sidebar=[self.file_selector],
        # )

FileSelectorDebug().servable()
2

This also applies to TextInput seemingly, but not if I deploy the app.