Issue when disabling Crumb in Jenkins and AD users - jenkins

Question

I have disabled the usage of crumbs inside my Jenkins, for some users it works, for some it won't.
In order to trigger a job remotely I am using a token for 'Trigger builds remotely' - I have tried to change the token, I can see the api call we use access the job, but fail on the crumb part
Since it is an AD user, one can argue that it is a local Auth issue, but the same user can trigger another job on the same Jenkins, so I don't believe it to be the case,
On the matrix security block - I have ticked all the boxes - just to see if that is the case - still not.
I've verified the job name, token string and length,
In order to disable Crumbs I use on the Script Console
(again, this works on another job, with the same user, and others as well)
import jenkins.model.Jenkins
def instance = Jenkins.instance
instance.setCrumbIssuer(null)
Yet.. I am facing with this error when trying to trigger the job:
Error class: <class jenkins.JenkinsException>. Exception occurred: Error in request. Possibly authentication failed [401]: Unauthorized
<title>Error 401 Invalid password/token for user: USER_NAME</title>
URI: /crumbIssuer/api/json
STATUS: 401
MESSAGE: Invalid password/token for user: USER_NAME
SERVLET: Stapler
Can any one explain why it is not working ?