An error occurred while saving the commentMichael G commented
It is rather important to keep track of the numerical sequence a set of animations may run. On the big edit window each animation has a small box to identify that animation, and in the Animation pane the same animations show an identical number. This allows the creator to keep track of each animation, both in the edit window, and the animation pane.
When we have one slide with one transition into a new slide and the new slide has 3+ animations very close together it becomes impossible to identify one from another in the edit window. The animation effects may lay on top of each other. In the Animation pane if each animation has a respective number, and that number relates (visually) in the edit window we can discover various animation effects by clicking on the numerical ID in the animation pane.
As stated above the animation sequence numbers with the "Start On Mouse Click:" show correctly in both the edit window and the animation pane; from "0 - 10+, etc. But if the animation controlling when a specific animation should begin is set to "Start With Previous", or "Start After Previous" all the sequence numbers reset to "0".
It might simply be a wishful imagination on my part, but I seem to remember in older versions of PowerPoint the sequence numbering of animations remained in proper sequence no matter when the animation was set to play. The only way to manually change an animation sequence number was to open the animation pane and drag an animation up, or down. This would then change the numbers of all the animations to play in the proper sequence.