Can't see Container props in Plasmic UI

Hi all,
If I have the App:

export function App({
  }: AppProps) {
  return (
    maxW="lg" py={{ base: '12', md: '24' }} px={{ base: '0', sm: '8' }}>

With this registration:

export function registerLoginWithCentredForm(){    
registerComponent(App, {
  name: 'LoginWithCentredForm',
  importPath: "./components/chakra/chakraPro/Application/Authentication/LoginWithCentredForm",
  props: {
    children: {
      type: 'slot',
      defaultValue: [
        { type: "component", name: getPlasmicComponentName("Container"),
          props: {
            py: '12',
            px: '0',
            maxW: "lg", 
            centerContent: false,

with this sub component registration:

import { BoxProps } from "@chakra-ui/react";
import { CodeComponentMeta } from "@plasmicapp/host/registerComponent";
import { getComponentNameAndImportMeta } from "./utils";

export const containerMeta: CodeComponentMeta<BoxProps> = {
  props: {
    py: {
      type: "number",
      defaultValue: 12,
    px: {
      type: "number",
      defaultValue: 0,

Then Why can’t I see container props appear in Plasmic UI?

Any help appreciated.

Looks like the only prop you registered on the LoginWithCenteredForm component is the children prop of type “slot”, which you can see on the left tree. You’ve registered default content for that slot, so if you insert a new instance of LoginWithCenteredForm, you should see a Container instance in that slot

Yes, the issue was “insert a new instance of LoginWithCenteredForm”.
Was expecting the old instance to update, but this was not the case.

ah, yes, the default slot content doesn’t propagate to existing instances