The commissioning process is hard to get right. With a complex building with a lot of technology and systems that need to interoperate there are thousands of checks, tests and fine tunings that needs to be performed as a continuing process. It is generally challenging to keep track of the responsibilities, statuses and results of all these tasks. Deviations and issues needs to be communicated between the trades, resolved, verified and brought to closure.
The owner needs to take an active part in this process and there is a big risk of miscommunication. It is hard to get an overview of the status and the result of tweaking one setting will affect another. It is hard to capture knowledge from the field and transfer it to the people that will later operate the asset.