When re-opening a project I saved without problem, I suddenly have input delay

Since some time I have a problem when I want to re-open a project which I was able to record normally.
When I open it again, I suddenly have a very strong input delay making it impossible to play.
I have adjusted my audio buffers to test but it does not make a difference.
I also hit real-time peak in audio performance despite not having this when I saved the same project the first time.

If I open a new project however (based on the same template) I have no input delay anymore.

Looking forward to any ideas.

I am using Cubase 10 on a Windows 10 PC with 32 GB RAM