Hi Ivan,

 https://www.telerik.com/account/support-center/view-ticket/1656871

I had also shared a detailed screen recording earlier, which might be helpful for your review:  https://www.awesomescreenshot.com/video/29561390?key=771efcaaa1033d73ce2166ade0603884

Kindly review this with the team when possible. Let me know if any further details are needed.

Best Regards
RAHUL

I analysed with the latest version Telerik.UI.for.Blazor 9.1.0. Still this bug exists.

Please let us know when it could be resolved in near future releases.

Although, I'm sharing a workaround to resolved it by correcting index on init:

Here is a workaround on this. I observed that when row is getting expanded it's creating new table row instead of adding to the expanded row, see in the screenshot:

Here we can see row attribute data-render-row-index has value 2. To fix it, created javascript code to rewrite value to 1:

1. Create javascipt method in _host.chtml to rewrite index value in expanded rows
   

   <script>
       window.JsFunction = {
           updateGridDetailRowIndex: function () {
               setTimeout(function () {
                   Array.from(document.getElementsByClassName("k-grid-table")[0].rows).forEach(r => {
                       if (r.getAttribute("class").match("k-expanded")) {
                           prevExpandRow = r;
                       }
                       if (r.getAttribute("class").match("k-detail-row")) {
                           r.setAttribute("data-render-row-index", parseInt(prevExpandRow.getAttribute("data-render-row-index")));
                       }
                   })
               }, 700);
           }
       };
   </script>

2. Add OnRowExpand event
   

   <TelerikGrid Data="salesTeamMembers" RowDraggable="true" OnRowDrop="@((GridRowDropEventArgs<MainModel> args) => OnParentRowDropHandler(args))" OnRowExpand="@OnExpand">

3. Inject IJSRuntime in razor page
   

   @inject IJSRuntime JSRuntime

   
   
   
4. Call script method by using IJSRuntime
   

   async Task OnExpand(GridRowExpandEventArgs args)
   {
       await JSRuntime.InvokeVoidAsync("JsFunction.updateGridDetailRowIndex").ConfigureAwait(false);
   }

Note: It's not a permanet solution but it will resolved the issue.