SPO CSOM method GetCustomListTemplates() throwing Internal Error

[HomerGreat]

Hi Devs,

trying to get saved/uplaoded .stp template by CSOM method https://learn.microsoft.com/en-us/dotnet/api/microsoft.sharepoint.client.site.getcustomlisttemplates?view=sharepoint-csom
** I have imported Pnp module and SharePoint client SDK.
** Specifically as below(site/web var, connection context and Site Context can see, but the template object throwing error)

$Ctx = Get-PnPContext
$Web = Get-PnPWeb
$RootWeb = $Ctx.Site.RootWeb
$ListTemplates = $Ctx.Site.GetCustomListTemplates($RootWeb)

** So the variable/object isn't loaded, looks like empty and can't continue with second creation part.
ERROR
Internal Error - Microsoft.SharePoint.Client.CollectionNotInitializedException: The collection has not been initialized. It has not been requested or the request has not been executed. It may need to be explicitly requested.
at Microsoft.SharePoint.Client.ClientObjectCollection.ThrowIfCollectionNotInited()
at Microsoft.SharePoint.Client.ClientObjectCollection.System.Collections.IEnumerable.GetEnumerator() ...

When I try to hover the $ListTemplates in debugger, it looks like loading for 0.5sec but then crashes and throwing that error.
Am I missing anything? Has been anything deprecated? Any suggestion? Thanks.