How can I access hidden colums in my nintex start form and change them there

in order to prevent changes in QuickEdit I want to hide columns and read and change them in the workflow using XML Call and XML Update actions. In the workflow I can reach the columns, in the start form I do not succeed.

How can I read and edit hidden columns in the Start form?

Thanks for your help

Making a colums total (SUM) with Views

Popular Drupal 7 modules such as Views Calc and Views aggregate plus are not available for Drupal 8, so I’m struggling with achieving the following :

  1. Making the sum of a column (of one integer field of list of nodes) without any custom code (no matter what I do with the “Use Aggregation” feature , I keep on getting a list of the values of entities meeting my criteria and not the sum).
  2. Make this (single) value available to another entity as a reference to the view (currently empty, possibly related to the fact that my views output is a list instead of a single value).

enter image description here