Platform Event Publishing Bug

This repository is a bug repro for Salesforce Platform Events when mixing "PublishAfterCommit" and "PublishImmediately" events in Apex.

Undesirable Behavior

All events that are published should actually fire. However, publishing a "PublishImmediately" event after a "PublishAfterCommit" event swallows the after commit event, and it never ends up firing:

EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay1')); // this event message will never fire
EventBus.publish(new MyImmediateEvent__e(Label__c='Immediate1'));

Reproducing

Defined in this repo are two platform event shapes, one that is "PublishAfterCommit" and one that is "PublishImmediately".

If you want to test it yourself, you can click here to have a bug repro scratch org built for you. Fancy.

The scratch org will come with a great streaming monitor app already installed, so you can immediately start testing. Simply subscribe to both platform events and start running some of these code snippets as anonymous Apex.

Variations

There are some interesting additional wrinkles and behaviors that shed some light on what might be happening under the hood on this one.

EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay1')); // this event message will never fire
EventBus.publish(new MyImmediateEvent__e(Label__c='Immediate1'));
EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay2')); // this event message will fire successfully

EventBus.publish(new MyImmediateEvent__e(Label__c='Immediate1'));
EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay1')); // this event message will fire successfully

Here's where it gets really fun.

insert new Account(Name='My Hero');
EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay1')); // this event message will fire successfully
EventBus.publish(new MyImmediateEvent__e(Label__c='Immediate1'));

EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay1')); // this event message will fire successfully
insert new Account(Name='My Hero');
EventBus.publish(new MyImmediateEvent__e(Label__c='Immediate1'));

EventBus.publish(new MyAfterCommitEvent__e(Label__c='Delay1')); // this event message will never fire
EventBus.publish(new MyImmediateEvent__e(Label__c='Immediate1'));
insert new Account(Name='Too Late');

Doing some normal DML, like inserting an SObject, allows the "PublishAfterCommit" event to fire successfully. My guess is the DML forces some kind of queue flush.