@████████- If the task is being assigned to the user properly (they receive it and see it in their inbox), and other users are getting the task assigned and receiving the email - and the only issue is this one specific user is not receiving the email, then...

I can only think of one reason on the Laserfiche side this would be happening, and that would be incorrect email address listed for the user.

Any other reasons I can think of, would be on the email side of things (like he has blocked the address these are being sent from).

Couple ideas to troubleshoot:

1. From the Forms Configuration site on your server, send a test email to yourself and a test email to the impacted user.  If you receive it, but they do not, then it's a good bet there is something in their email settings that is preventing it (like blocking the sender address).  If they do receive it, then I'd look deeper at the user record for Forms to make sure the right email address is listed.
2. Verify what email address is listed for the user in Forms.  They can of course verify that in Forms from the menu at the top-right.  But here's a database query you can run on the LFForms database if you'd like to dig deeper in to it: 

   /*search current user records for specific user*/
   SELECT *
   FROM [LFForms].[dbo].[cf_users]
   WHERE [username] = 'USERNAME';
   
   /*search historical user records for specific user*/
   SELECT *
   FROM [LFForms].[dbo].[cf_user_snapshot]
   WHERE [username] = 'USERNAME';