Set gameplay tags via blueprint and update at runtime

I recently discovered the Custom Gameplay Tags via the UI section in your project settings.
I was hoping to use with my blueprints to flag when an NPC is alive or dead.

I thought I only had to create the tag and then set it and then I could call different code depending on the tag but this doesn’t seem to be working so I’m wondering if I did something wrong. Are these custom tags not the same as the tags you can apply to an actor in the detail panel?

Here’s my setup:

Anyone know if this is possible? Or if it’s not, is there an alternative to gameplay tags that can be used that you can change at runtime?

AFAIK GameplayTags are used by AbilitySystem plugin. You can’t change them are run time. If you want to use Tags with NPC you can use Tags array available in actor. Which can be modified at run time.
Check out Tags variable in AActor

Dont know if its possible in 4.15, but im in 4.23 and heres the deal there:
The Actor class has by default a Name type array variable called Tags, which stores all gameplay tags this component is assigned to. You can call it and manage it the way you want it like its a simple array (incl. at runtime ofcourse).
Same for Actor Components, but instead they have by default a Name type array variable called Component Tags