I use Ext.Net Razor Pages template project.
The server code Label lbl = this.GetCmp<Label>("lbl") returns label object.
But label's Text and Html properties are just empty strings ("").
However assignment lbl.Text = "some string"; works fine.

The code for Ext.Net Razor Pages:
@page  "{handler?}"
@model ExtDemo1.Pages.DirectEventsModel
    ViewData["Title"] = "DirectEvent";
    var X = Html.X();
<ext-section target="Main">
    <ext-container region="Center" scrollable="true" paddingAsString="30 20 30 50">
            <ext-button text="Click Direct" onDirectClick="ButtonClick" />
            <ext-label id="lbl" text="ext-label"></ext-label>
using System;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using Ext.Net;
using Ext.Net.Core;
using MojeeIO;

namespace ExtDemo1.Pages
    public class DirectEventsModel : PageModel
        public void OnGet()
        public IActionResult OnPostButtonClick(string message = "default text")
            Label lbl = this.GetCmp<Label>("lbl");
            var txt = lbl.Text;              // returns empty string
            lbl.Text = $"{txt} {message}";   // works fine
            return this.Direct();