Thank you for sending your project, I've figured it out! The cause of your confusion is the Sync button on the Dopesheet view. When enabled, the dopesheet shows the rows for the curves that are visible in the graph, and this hides the keys for attachments and draw order because they have no curves. I think it is not a bug but an intentional implementation, but it certainly could be confusing, so we will discuss whether this should be fixed.
Sorry, my first response was not accurate. The reason the attachment keys and the draw order keys were not displayed was simply because the visibility dots of them were not turned on the Graph view. You can see how the Sync button works in the video below:
Thus, the Sync button determines what is displayed on the dopesheet based on the Graph view, so if you don’t want to see both the Dopesheet view and the Graph view at the same time, you should turn it off.
