This issue occurs because Tasks in Salesforce are not linked to Accounts using the AccountId field. Instead, Tasks must be associated with Accounts through the WhatId field. When the import is configured to match or map using AccountId, Salesforce does not correctly associate the Task with the Account, causing the records to fail to appear on Account records after import.
In this case, the user imported a file containing Account ID, Due Date, Subject, and Status, but after the import, no Tasks appeared under the corresponding Account records.
During troubleshooting, the import setup was reviewed and tested using a single sample record. It was confirmed that the import wizard was configured to map the CSV AccountId column to the Task AccountId field, which caused the issue.
To resolve this, the mapping was corrected by:
Mapping the CSV AccountId column to the Task WhatId field in Step 2 of the import wizard.
Re-running the import using sample records to validate the fix.
After this correction, Tasks were successfully imported and correctly associated with their respective Account records.