Can you provide the exact target attribute that is being targeted? Is it just "company"? If so, that attribute is not a part of the SCIM Core Schema. Attributes that are not a part of the SCIM Core Schema as defined in RFC 7643 must have a fully SCIM compliant URI as outlined in section 10.2.1 - https://datatracker.ietf.org/doc/html/rfc7643#section-10.2.1.
Try renaming that attribute in your service and in the AAD provisioning schema for your target system to be something like urn:ietf:params:scim:schemas:extension:MyAppName:2.0:User:company and our service should handle it correctly.