In London, when a request is created, value of a reference variable is not populated on the Requested Item record even though it is populated while creating the request.
This issue is reproducible on Service Portal, as well as Platform catalog.
This issue can happen if the name of the variable is the same as Variable set.
Starting London, a catalog item cannot have a variable set and a variable with the same name.
You can find this information in our release notes for London under "Modifications to a variable set" section.
To solve this issue, modify the name of either the variable set or variable so they are not the same.