When we attempt to update the field AnnualRevenue using the SOAP API, the response says the record is updated, however the AnnualRevenue field does not persist the change. If we try to update the field manually using the Lead Database, changes to this field are not persisted either.
The other thing can sometimes happen is that it might be an Account Field synced over from SFDC. We block changes to those fields by default because SFDC is the system of record for them in many cases.
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