Panel sprite stretched out turns black in preview

I have a game where I use a Panel Sprite as follows:

As you can see, the Panel sprite is quite streched out. This still works in the preview:

I chose the previous width on purpose, since it’s the border case of when it goes wrong. Namely, if I stretch it a little bit more like this:

Then in the preview, the background turns black:

The example is a very basic game without events. I don’t think the above is desired behaviour?

Thank you in advance!