When I first created a Herald Rule, I simply wanted a build plan to run on Harbormaster when a commit happens in one of our git repositories in Diffusion. The problem is, I added the trigger object to be triggered on commit, then added the action to run my build plan; I left the condition empty since I didn't need a condition.
I tested this, and much to my dismay, it didn't build on commit. After asking around, it appears that this only works if you have a condition and since my condition was empty, it didn't match. As a front-end developer, this is an extremely weird behavior. I didn't add anything nor did I even click or touch the condition part. Herald definitely needs to add the possibility of no conditions as a default.