In my organisation we are Using custom field called Lead_Source__c in lead object
In opportunity level we are using standard field called LeadSource
Now, i am unable to map it's not showing standard picklist in lead mapping.So,i am mapping to a custom field in opportunity.
And i set up a process in opportunity on creation & field update with updating standard LeadSource if custom lead source field have any value.
It's working fine.Now the problem is above process is failing because i have a validation rule on opportunity if any opportunity updates means NOT(IsNew()) restrict users to modify LeadSource if Lead category is marketing.
As per the community i understood process builder runs on system mode but why validation rule fires in this case