[UBP] webhook error in usage component - Invoice did not contain exactly 1 line item

[jldec]

Invoice finalization webhooks for individuals on paid UBP plans appear to be failing in some cases.
Webhook failure was traced to log message below which points to billing.go L312
More details including webhook json in slack thread (internal)

    "level": "error",
    "message": "Invoice did not contain exactly 1 line item, we cannot extract quantity to reflect in usage.",
    "file": "billing.go:312"