Abnormal response for one project when querying issues with attachments

Hey All!
Our apps indexes attachments in Jira Cloud. First of all, it queries issues within projects, as follows:

GET /rest/api/3/search
with the following parameters: fields=attachment,project and jql=attachments is not EMPTY

It returns the list of issues with no Attachment field, while the Project field is present everywhere.

Here’s an example, of the response part:

Such behavior is observed when we use REST API v.2 and v.3. This issue persists in one project only, while in others everything seems to be ok.

Does anybody have an idea why it happens this way?


Sincerely, Vadim