Thanks again Tatiang.
I am still using Thunkable Live on the mobile to test and it still crashes with the correct blocks.
I have previously isolated the url that I construct to call the API exactly as you have described and copied that straight into a browser to test it works and it does… I have also confirmed that it works in the app pre-JSON converstion and parsing and again, I get the correct response from the server.
I will share a link with you once I work out how to do that as Thunkable is a new environment for me, thanks for taking the time to help me out here.