Stunner - Error once updating form fields

Once trying to add or update values in any of the User Task' actors fields (Assigne & Groups) an exception is being produced.

Error: AdapterNotFoundException: Adapter of type [org.kie.workbench.common.stunner.core.definition.adapter.DefinitionAdapter] not found for [org.kie.workbench.common.stunner.bpmn.definition.property.task.UserTaskExecutionSet]

See attachment.

I happens for most of the fields actually