Each Request Offering is attached to a specific Service, see below. Hence that Request Offering is only available in the pick list for Service Level Package to which it is attached. In your case Address Change is not attached to the service: Customer Experience and hence giving you validation list error.
So the next question should be, can we add same Request Offering to multiple Service?
Maybe I'm not understanding the use case here but any reason why you would want a request offering to be included in multiple Services? I can understand a request offering needing to be in multiple service level packages, but not sure how a request offering can be spread out to multiple services.
Sorry for confusion. You are right there won't be any need to add same Request Offering to Multiple Service. However, it seems the OOTB request offering like 'Address Change' is only available for Service: Service Request. So, actually it is the Service and not Service Level Package that has the picklist defined.
In your case (pic), it shows Service as "Customer Experience" and hence you would not get Address Change as an option to link it to that package and would show validation error.
Thanks for your response Vivek and Elyse.
I have a use case to want Request Offerings to be included in multiple Services. For example, Customer Experience is a super-set service that sits on top of other supporting services, such as Service Desk, Facilities Management, Marketing Services etc. Therefore, each Customer Experience Service Level Package will need to contain request offerings from the different supporting services, such as Service Desk, Facilities Management, Marketing Services etc. Is this achievable?