401 unauthorized
The secret is missing, wrong or revoked. Copy the connection URL again from the zapbip number, or ask for a new agent. With the Bearer form, the header isAuthorization: Bearer <secret>.
The message is queued
delivery: "queued" means the 24-hour window is closed. The message waits and arrives, in order, as soon as you write to the zapbip number.
Upload errors
The bytes are rejected before anything is stored:
See create_upload.