Hello there, Matteo. Let me shed some light regarding the custom management reports.

Upon granting a user full access to the management report, the invited user will be able to access the default report. However, they cannot view or generate any custom reports created by other users directly. 

Therefore, you'll need to share the report manually with the other user. 

Here's how: 

1. In Management reports, locate the custom report.
2. Click the Action dropdown
3. Select one of the following options:

• Send: A window opens where you can edit recipients, subject line, and message before emailing the report PDF.
• Export as PDF: Download a PDF version of the report to your device.
• Export as DOCX: Download a DOCX version of the report to your device.

I've attached a screenshot for visual reference.

 
Refer to this article for more information: View and edit management reports in QuickBooks Online. 

For a detailed overview of each user role, including their respective access levels, refer to this article: User roles and access permissions. 

Moreover, you can add your accountant in QuickBooks Online. This access lets them view and modify your books, perform necessary corrections, reclassify transactions, and write off invoices. 

I'm always here to help whenever you need assistance managing your invited users and custom management reports. You can enter any queries by clicking the reply button below.