Hi, thanks for using Microsoft Q&A Platform.
Can you provide more information about how you're reproducing this, as well as model, and code details? Meanwhile, here is a similar issue reported; please take a look to see if it helps your query.
Github issue: https://github.com/Microsoft/Cognitive-CustomVision-Windows/issues/19
Similar threads: https://stackoverflow.com/questions/51611116/customvision-operation-returned-an-invalid-status-code-notfound
Regards,
Vasavi