Assigned To column (or any column that uses People Picker) cleared after clicking Edit Item in a Task List

Question

Our SharePoint Foundation 2013 is experiencing a weird issue. It only happens in Task Lists. For example:
Create a new Task in Task List and fill the Assigned To field with a user from the People Picker list. The People Picker works fine as all users in Active Directory are appearing.
Save Task.
Edit Item the task that was just created.
The Assigned To field is now cleared for that Task.
It used to keep the user that was in the Assigned To column.
Are there any suggestions on what may have caused this or what I can try to fix this?
This was after some Windows updates were installed end of August.

Answer 1

Hi PauIT,
According to your post, my understanding is that the “Assigned To” field is cleared when you edit a task item in the Tasks List.
I recommend that you can enable server rendering on the list view Web Part for the Tasks List to solve this issue.
To do this, please follow the steps as below:
Open the Tasks List in your site, add a new task item, type the user name in the “Assign To” field and save it.
Select the new item, click “Edit item”, then go to the Gear icon, click “Edit page”, click the drop-down arrow in the upper-right corner of the Web Part for the Tasks List, and click “Edit Web Part”.
On the right side of the page in the Web Part properties controls, click the plus sign (+) on the “Miscellaneous” section, select the “Server Render” in the “CSS Render Mode” section, then click “Apply”, “OK” and save the changes of the page.
Then, you can see if the “Assign To” field in the new item’s Edit Form has the corresponding values.
There are some similar threads for your reference:
http://sharepoint.stackexchange.com/questions/87089/assigned-to-column-text-hidden-but-filterable
http://support.microsoft.com/kb/2924913/en-us
Best Regards,
Yumi Fu