Page Refresh causes "Object reference not set to an instance of an object"

Hi

After moving some labels and textboxes around from 1 column page layout to 6 column, suddenly page refresh causes "Object reference not set to an instance of an object.". This is right after starting app, navigating to page and hitting F5 on browser. Same Fields, same buttons...just a rearrange of components into 6 col page layout.

dotnet: warn: Microsoft.AspNetCore.Components.Server.Circuits.RemoteRenderer[100]
Unhandled exception rendering component: Object reference not set to an instance of an object.
System.NullReferenceException: Object reference not set to an instance of an object.
at PPL.Pages.ItemsFormMulCol.b__0_1(RenderTreeBuilder __builder3)
at Radzen.Blazor.RadzenCard.BuildRenderTree(RenderTreeBuilder __builder)
at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
at Microsoft.AspNetCore.Components.RenderTree.Renderer.ProcessRenderQueue()

Assistance appreciated.
Thanks
Mike

Problem solved. I had a row that was not nested inside the Template Form.
I'll leave this here for anyone else having similar issues.