Video editor only renders one channel

I’m using the new Blender 3.0 Video Editor and I have a different clip on different channels, but when I render, only the first channel is shown.
On my workspace everything looks fine (I apply transformation effects to scale every clip so I can see the others behind and I blend as Over Drops). On past versions that should be enough to render my video the same I see in the editor, but is not working for some reason.
Any thoughts?

EDIT: I just realised I no longer need to add Transformation to scale the clips. Looks like this new version has scale transformations within the same clip. Yet, the problem remains as I can only render the bottom channel + audio channel

What is the blend mode of the top clip? It should be set to alpha over if you want to see the clip under it.

Yes, it’s alpha over

I have done further tests and looks like the problem is in all the clips except the one that gets rendered.
Maybe it’s their codec or something else but they’re all coming from Whatsapp videos while the one that gets rendered is an usual mp4 file.

That said, still weird that playback in Blender’s VSE works well but when attempting to render, they are not visible