Some country plugins have 'xxxx' or others defined for the format type. That can generate values like 0123 that start with a 0. The JSON Export Type fails to render them as a string so it's invalid.
Edit: this is mostly a CLI bug. Will close with a fix there, however the bigger issue is the DT metadata isn't being passed to the ET right now. Will resolve that separately with the CLI.
Some country plugins have 'xxxx' or others defined for the format type. That can generate values like
0123
that start with a 0. The JSON Export Type fails to render them as a string so it's invalid.