When cloning Python environments in the ArcGIS Pro Python Package Manager on a disconnected machine, the resulting environment is missing files.

Workaround

Create the desired Python environment on a different machine that is connected to the internet. Zip this environment up and physically move it to the disconnected computer. Place the unzipped Python environment in one of the two recognized locations for Python environments (ex: C:\Users\[user]\AppData\Local\ESRI\conda\envs\) and ArcGIS Pro picks it up.

Another way around this issue is essentially cloning the base arcgispro-py3 environment:

1. Navigate to where the default Python project environment is located, it is listed in the Python Package Manager but is generally located at C:\Program Files\ArcGIS\Pro\bin\Python\envs
2. Right click and copy the environment folder for arcgispro-py3.
3. Paste this folder in the current location (administrator privileges required) or the other recognized environment folder located at C:\Users\<user>\AppData\Local\ESRI\conda\envs
4. Change the name of this folder to the desired environment name.
5. ArcGIS Pro picks this up as a Python environment.

Steps to Reproduce