I have a simple Grid with custom detail template
<Telerik.Blazor.Components.TelerikGrid Data="@GridData" FilterMode="Telerik.Blazor.GridFilterMode.FilterRow" >
<GridColumns>
<Telerik.Blazor.Components.GridCheckboxColumn Title="Selected"></Telerik.Blazor.Components.GridCheckboxColumn>
<Telerik.Blazor.Components.GridColumn Title="Name" Filterable="true" Field="@nameof(GridItem.Text)"></Telerik.Blazor.Components.GridColumn>
<Telerik.Blazor.Components.GridColumn Field="@nameof(GridItem.Date)" Filterable="true" Title="Date"></Telerik.Blazor.Components.GridColumn>
<Telerik.Blazor.Components.GridColumn Field="@nameof(GridItem.Id)" Filterable="true" Title="Id"></Telerik.Blazor.Components.GridColumn>
<Telerik.Blazor.Components.GridColumn Field="@nameof(GridItem.ParentIdValue)" Filterable="true" Title="Parent Id"></Telerik.Blazor.Components.GridColumn>
<Telerik.Blazor.Components.GridColumn Field="@nameof(GridItem.HasChildren)" Filterable="true" Title="Has Children"></Telerik.Blazor.Components.GridColumn>
</GridColumns>
<DetailTemplate>
<div>Custom Template</div>
</DetailTemplate>
</Telerik.Blazor.Components.TelerikGrid>
And here is what it looks like. Filters are moved one column to the left. When I remove DetailTemplate everything is ok.