Hi @Jimmy4 , based only on the error message is difficult to say what is the issue. I do not think that this is a general internal issue of Studio but I think it is based on the specific case and of the external data setup. So possible reasons could be that the server is not present, the object containing the service etc. is removed or renamed or the service was changed etc.
You can try, if the thing and the service (something I see GetMachineModel) are registered as external data- you can remove them and add it again to see if the object is still visible in the network and you can register it in the external data section again. And then to make a console.warn printing of the results of service … etc.
Another point is - you can try to execute the model on Thingworx to see if there is no problem with the service itself.