Hi @Ppantaleo,
Thanks for sending along the additional screenshots. This is definitely a tricky one!
From what you describe, it sounds like a submission or a small subset of submissions are referring to non-existent data. Two places to check are to make sure that submissions have publications and sections associated with them. You could try the two SQL queries mentioned here: OJS 3.2.1.1 Slim error message on Dashboard submission page. This post is about 3.2.1, but it should still apply here.
Regards,
Erik
PKP Team