Registering plugins for Actions fails

[Martype]

[CrmPluginRegistration( message: ***_SetStatusOf*****DetailsRequest.ActionLogicalName, entityLogicalName: null, stage: StageEnum.PreValidation, executionMode: ExecutionModeEnum.Synchronous, filteringAttributes: null, stepName: "***.*****.Global.Plugins." + nameof(PreValidateSetStatusOf*****Details), executionOrder: 1, isolationModel: IsolationModeEnum.Sandbox )]

There is nothing wrong with my message name. Manually registering the plugin step using the same message name works without any problems. Unfortunately spkl even unregisters my manually created plugin step, therefore I had to temporarily comment out the correlating CrmPluginRegistration.