Here’s how I’d recommend setting it up. I have a setup for sprint in a game I’m working on.
I don’t set a boolean value when I sprint. I alter the Character Movement value ‘Max Walk Speed.’ This dictates how fast your character goes when you’re providing movement input.
As for the animation graph, I’d recommend just using the value Speed you already have in your animation blueprint and using that as an input to a one dimensional blendspace that has speed as its variable.
Also, if you wish to access booleans in your animation blueprint, make sure to uncheck ‘Context Sensitive.’ It will disallow you from seeing that variable since it was created outside of the anim BP. I provided a screenshot that accesses my two variables I created for run and walk speed, and access of the boolean will be identical.
