OfficeJS Word add-in development: Office.context.document.getFilePropertiesAsync() in Firefox always results in status = error

Question

I am hoping some OfficeJS folks can identify if this is a known issue in FF for the Word Add-in API. Given code

 private getFilePropertiesAsync() {
    Office.context.document.getFilePropertiesAsync((asyncResult: AsyncResult<Office.FileProperties>) => {
        if ((Office.AsyncResultStatus.Succeeded !== asyncResult.status)) {
            this.logger.error(asyncResult.error.message);
        } else {
            // do stuff
        }
    });
}

the asyncResult.status in Firefox is always an error. Any Chromium browser or IE (or desktop) is fine.

Office.context.document.getFileAsync() seems to be fine in FF (and everywhere else), which is what makes me suspect getFilePropertiesAsync() may have a bug. I didn't turn up anything meaningful on the MS Forums or Stack Overflow, though I admit to not spending hours searcing.

Happen to be using Java, Angular 8 for the taskpane app, in FF 84, Win 10 1909. Coworker sees the same behavior for this add-in