Hi @adam_robinson !
You can debug in Postman console, use ctrl+alt+C to show console, and then use console.log to see what of your variables is undefined. For example, in the pre-request scripts tab at the collection level:
Then run any api (I try with list calls, as they does not need any parameter):
Do a console.log entry for every one of environment variables, to see which are defined and which is the problematic one.
This an example of my environment variables definition:
(The ones marked in the square is what you should have defined)