CleanRip lets you change the chunk size, so three chunks is a possible thing it can output. I don't know what the default is, so I took a guess that showed enough things that you'd probably be able to figure out what was going on, which you did.
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
