EventBus rule is not picking up any data that is flowing through EventBus

Current state:

Account A has:

1. EventBus A with EventBus rule
2. Lambda that makes a request to EventBus A.
3. EventBus rule that targets EventBus B
4. EventBus rule that has custom Event Pattern to match all events:

{
  "source": [{
    "prefix": ""
  }]
}

Account B has:

1. a global EventBus B
2. an allow list that blocks requests from EventBus A (only allows data flowing from allow listed sources)

My goal:

1. See data flow through EventBus A in "monitoring" metrics tab (observed behavior: this is done and working)
2. See data flow through EventBus A's rule but not to the global EventBus (observed behavior: this is NOT working - all metrics in the monitoring tab show "no data available")
3. See "Matched Events" metric increment for the Event Bus A Rule. (observed behavior: this is NOT working - "no data available")

I can't seem to figure out why the EventBus A rule, which should match all events, isn't matching with any of the events that are flowing through EventBus A? I also tried allowing all events to flow through the rule and this also produced the same observed behavior.