Do not run it inside the Trainz Built-in directory. Run it from your desktop. You will see a UI with two panes: left for folder structure, right for file preview.
Do you have a CDP that refuses to open? Share the KUID in the comments below, and the community will help you extract it safely. Trainz CDP Extractor Verified, CDP Explorer, Trainz asset extraction, TRS22 modding, faulty asset repair, pevsoft tool. trainz cdp extractor verified
Even verified extractors are read-only, but mistakes happen. Copy your locomotive_pack.cdp to a Temp folder. Do not run it inside the Trainz Built-in directory