Query to extract all items with Supply Allocations

We are trying to extract data for all items which have supply allocations. The data needs to match what we see on the Review Supply Allocations page.

Attached is the query we are using. We have observed that some items are not showing in the report when we run the query. The same records are fetched in the report after we query the item from the UI screen. Need some help to understand if there are any tables which have this data stored without requiring us to first check item on UI screen.

We wanted to check if the tables we are using are correct and would have all the required data populated?