Valuable lesson learned: When your Mac starts acting weird, the first line of troubleshooting is to restart the Mac. You may be surprised how often this fixes a mysterious problem.
Don't really know what you mean by that, but in general I have found KM to be a very solid, stable, robust app. Bugs and inconsistencies are very rare.
To be candid, most weird problems are some type of user error and/or misunderstanding. That is excepting, of course, the security and accessibility issues that started with macOS Mojave, and have gotten worse with each new release.
One very important skill to learn with any programming tool, and KM is a programming tool, albeit a visual one, is debugging. This means finding bugs in your code (Macro Actions) and design, not in the tool itself.
Some Key Debugging Techniques
- To inspect Global Variables, use the KM Preferences > Variables panel and/or the Window > Value Inspector
- Use the Display Text In a Window Action at key places in your Macro to show values of all types of Variables.
- Use the Macro Debugger to step through your macro to observe which branches it takes, and to view data from #1 at each step.