While trying to split off a new blueprint ID for reporting the broken world issue, I ran into a new issue:

If you do a 0 client "Build and Reload" and then try and "Upload Last Build", everything will seem to work until almost the very last stage at which point the SDK will bail out with the following errors (image attached).

Primarily of which is "udonProducts must be an array: null".

Despite the error, the blueprint ID is already blank.