Hi,
Under Oracle APEX 24.2.11, I have a modal page 17 that call another modal page, page 46. I put a dynamic action on page 17 to regenerate the region “Tâches du Projet” on closing or cancelling the modal page P. 46 called from the page 17:

The page 46 create a new “Tâche du projet”. There is not any condition on P. 17 server-side or client-side in the DA to regenerate this region. But it is not regenerated on P. 17 when you create this new “Tâche du projet” on page 46. It only if you close P.17 and reopens it that you can see the new “Tâche du projet”.
Best regards.