Red square on Lens Flare

I’ve got a really odd issue when using the lensflare. As you can see from the attached image, there’s a small red box positioned where the light is…
Can anyone advise what I may have done to get this? The code is directly lifted from the lensflare demo.

My guess is that there is a texture its trying to load for that lensflare, and it’s missing.

Do you have any red errors in your network tab?

Thanks for getting back to me… When I checked there was nothing missing, but I had made a slight alteration from the example, replacing the first texture (which is a big lensflare) with one of the later ones which is smaller. It looks like this larger sized flare image covers up the red box…

Possibly related: How does Lensflare set up transparency?