Some accounts do not show in reports even if Show Zeros = T and Activity Only = F

In the report builder > More Options tab
Show Zeros = True, accounts that had previous transactions and now have zero balance will be displayed.
Activity Only = False, accounts that do not have activity but used to have transactions will also be displayed.

Alternate solution to trigger the accounts in being included in reports
1. Transactions > Financial > Make Journal Entries.
2. Create journal entry that debits and credits the account for the same amount.
3. Save the journal entry.
4. Edit the journal entry > More Actions > Delete.
5. Go back to the report.
6. Reports > Financial > Income Statement > Customize.
7. More Options > Show Zero = True > Activity Only = False > Preview.
8. Account now displays in the report.