The full message is "Constant data persistence has been disabled for this request because automation already applied constant data. Turn constant data persistence off in OCLC Service Configuration."
This message is referring to the Persistence setting in Service Configuration. This message appears because you have persistence enabled, but an automation applied the default constant data first. You do not need to do anything, and you can proceed with the request as normal. But you may wish to disable the persistence setting if you have automations set up to apply constant data. You can do this in Service Configuration under WorldShare ILL>Interlibrary Loan Options>Persistence Setting. Please see Additional Information below.