I have a project which I started in Ae 2023.6. When Ae 2024 came out I worked at the project there, having converted it into a 2024 project version. I finished the project, sent it to the client and yesterday I got a note for some corrections to make in it. So I open up the project in Ae 2024 and get this:

I hit OK and get this:

I hit OK and get an empty timeline:

I have tried saving the project in 2023 version and opening it in Ae 2023 and I get the same empty project there. And yes I tried "saving under a different name".
What am I to do? I am about to lose my client, Adobe...