Blueprint Debug Case Study
Prerequisites : This is a debug case study collection of forum threads, you need to have to know blueprint fairly well.
Skill Level: intermediate to advanced
Note: Feel free to add thread to list and put them into proper subsections, please don't add trivial newbie error or blueprint bug that Epic will fix. This is suppose to be a wiki that keeps really good examples of how using blueprint wrong unintentionally that cause a problem, but solved with a correct approach.
Blueprint's event system is a concept easy to take in, but also easy to overlook. Many people assume events run like how they imagined, like I will run EventA and then EventB, or take results from different white execution line, or try to do too much in level blueprint instead of structure their hierarchy of blueprints properly, or use CastTo whenever they can that leads to dependency problems.
This page might not solve your problem, but it offers good examples that how you might run into a problem, and how to solve it with efficiency and correct manner.
Order of Event Execution
Use input to disable input
In this forum thread, it presents a classic example of how you should not depend on the execution order of events.