Why does the datagroup catalog editor show those strange units?
I tried this my end , but I'm seeing proper units while creating a new catalog Item/ Type.
Can you please check by creating a new Destination file ? , since units setting gets enabled when you create a new destination file .
Guess you might be using some existing destination file ...
I do use an exisiting destination file - "NODE_Structural.xml".
The screenshot below shows both the dialogue box for a new item, and the start of the destination file.