Batch completion event generated before batch is completed

We are trying to test impact of CLS varance of leaving batches in WIP status over period end. In test, created batch, issue materials, and leave batch in WIP status. After running GMF Period close process PRELIMINARY, Recreate batch layers, Actual Cost Process, Preprocessor, Detailed Subledger we see batch completion events generated for the batches left in WIP. Expected to see batch release but no batch completion until batch is completed in following month. We are running PMAC costing. What am i missing here? Why are the completion events generated for WIP batches?