Reconciliation Rule doesn't work. Discovery source does not update an attribute, even if the "Apply to all attributes" is ticked.
There might be another reconciliation rule on same CI Class that picked a particular field.
This is working as designed.
For any CI Class, if a reconciliation rule picks a specific field, then other discovery source with reconciliation rule that has "Apply to all attributes" switched on will skip updating that field.
This is also documented as below:
"If you want to authorize a data source to update specific attributes in a table, list these attributes in the reconciliation rule for the data source. A rule that grants access to specific attributes in a table overrides other rules with an empty attribute list that grants access to the entire table."
The solution is to open the reconciliation rules with "Apply to all attributes" switched on in CI Class Manager,
on Attributes tab, switch off "Apply to all attributes", then pick all the fields manually.