OJS 3.3 submissions API: missing issue id in json output

Hi, any hint on why we are not finding the issue id using the submissions API of OJS?
Best regards

Describe the issue or problem
Using OJS 3.3 submissions api we noticed that issue id is missing, despite is declared in documentation as included in the output (issueID field).

Steps I took leading up to the issue
We used the api https://riviste.unimi.it/index.php/SSMD/api/v1/submissions/

What application are you using?
OJS 3.3.0-13