You presumably have two exports which contain shape keys.

You should ask for help in a Blender forum.

This is an issue with Blender itself.

Yes, the file is needed.

You can click on Scene Export and it will export the animation.

It's a bug that the animation doesn't show up as its own item in the list.

Please upload your .blend file.

You need to use Blender 4.1 or later.

This is the first time I've ever seen this system. It's much more complicated than the old one and I don't yet understand what has changed. I didn't make any substantial changes to the property system for the 3.3 release, so it currently seems more likely that something in Blender 4.1 broke it.

You should be able to work around this by copying the linked collection into the local .blend file, exporting, then undoing your changes.

Please post your console window output.

Restarting Blender will fix this.