Didn't have problems using global events so far but had some problems using global variables but i learned how to fight against those problems i can work normally now. First you have to beware when changing or deleting prefabs that have global events or variables on them, that can cause disruption in those events / variables. Use local variables instead of globals, it can be harder sometimes but it is safer way (use more get / set fsm action to achieve this) and for events name them properly, idk is that going to help but since i didn't have any global event switching problem so far in my case i always name events like this: "Group of event / Name of event" for example GUI / Activate, GUI / Deactivate, INVENTORY / Show Inventory, INVENTORY / Hide Inventory, STATS / Hide stats.....
This problem can mess your project pretty much sometime so backup your project always, we all hope some solution will be found fast.
Cheers!!!