Layout builder on widget using Custom Sidebar

Hi,

Whilst placing a Layout Builder widget on a Custom Sidebar(used Custom Sidebars plugin), I can create a nice layout. After pressing done in Layout Builder and saving the widget, the sidebar shows nicely on my page.

However when I return to the Widget Area (Under Appearance) and selecting the Layout Builder again because I want to edit the current layout, it shows me only an empty layout in the Layout Builder. So the page layout seems to be gone. It is still showing on the live page, but I seem unable to edit it anymore.

If I try again it does replace the earlier layout but again I cannot edit the content after first creating it.

As you can see on: wp2 .windmillp2p. nl/ ?page_id=48 (added some spaces)
The right sidebar layout shows up nicely as created in Layout Builder. I used the following custom CSS from another post on this forum to be able to use same button sizes:

.videobutton a {
    width: 100%;
    height: 20px;
}

Can you please help as the Layout Builder gives me the right tools to fill the sidebar and still be able to use some custom elements which are not theme related.

Kind regards,
Erik