Event Module Multiple Sessions - Cancellation Issue

When adding a "Cancel Event Registration" processing step to a form for a multi-session event module an error is shown when saving the form with the cancellation step that says "Failed UniquenessRequirement". This event module uses an Eloqua generated UID.

When switching the event module identifier from the Eloqua generated UID to email address, the error goes away, but this is not the functionality that is desired. We want contacts to be able to register for multiple sessions, not just one.

Knowing this, does the "Cancel Event Registration" step only work with events that use email address as the identifier? And if so, is there a way around this?