Configure unconstrained delegation for BULK INSERT
Your configuration looks solid. SPNs and Delegation are configured as I would have done it myself.

The only thing which you haven't explained are the file/share permissions. This is where my solution steps in.

Solution 1  (Personal Account)


Verify that your personal account is allowed to access the file on the file server's share  


your personal account needs at least READ permissions at the share permission level or in most cases you might see EVERYONE has READ permission.
your personal account needs at least READ permissions at the file's permission level
Check permission inheritance at file level for that one file  


Reboot the SQL Server after changing the file permissions or cycle the SQL Server service.

Alternatively: Log in to the SQL Server with your personal account and connect to the share and open the file.

Open SSMS with your personal account.  
Open up a connection to your SQL Server instance with Windows Authentication.


Verify you are connected to your instance with the SQL Server service account with the script you have used before.  

Perform the import with BULK INSERT 


Solution 2 (SQL Server Service Account)


Verify that the SQL Server service account is allowed to access the file on the file server's share  


the SQL Server service account needs at least READ permissions at the share  permission level or in most cases you might see that EVERYONE has READ permissions.
the SQL Server service account needs at least READ permissions at the file's  permission level
Check permission inheritance at file level for that one file  


Reboot the SQL Server after changing the file permissions or cycle the SQL Server service.  

Alternatively: Log in to the SQL Server with the SQL Server Service Account and connect to the share and open the file.

Open SSMS with the SQL Server service account.  


Runas: your_domain\SQL_Server_service_account
Provide password

Open up a connection to your SQL Server with Windows Authentication.  


Verify you are connected to your instance with the SQL Server service account with the script you have used before.

Perform the import with BULK INSERT 


BULK INSERT permissions


  Security Account Delegation (Impersonation)  
  
  If a user uses a SQL Server login, the security profile of the SQL Server process account is used. A login using SQL Server authentication cannot be authenticated outside of the Database Engine. Therefore, when a BULK INSERT command is initiated by a login using SQL Server authentication, the connection to the data is made using the security context of the SQL Server process account (the account used by the SQL Server Database Engine service). To successfully read the source data you must grant the account used by the SQL Server Database Engine, access to the source data. In contrast, if a SQL Server user logs on by using Windows Authentication, the user can read only those files that can be accessed by the user account, regardless of the security profile of the SQL Server process.


Reference: BULK INSERT (Transact-SQL)