The field 'Loan_Amount__c' either does not exist on the Contact object or it is not of type currency.
Hi ,
You need to check if somehow you missed field level security Click on the field and check field level security.
- From Setup, open Object Manager, and then in the Quick Find box, enter the name of the object containing the field.
- Select the object, and then click Fields & Relationships.
- Select the field you want to modify.
- Click Set Field-Level Security.
- Specify the field's access level.
- Save your changes.
https://help.salesforce.com/s/articleView?id=sf.users_fields_fls.htm&type=5
