All the divisions by 100 seem unnecessary. The TargetHealth value isn’t a percentage (you need to divide by the max for that, not 100). But that’s not the issue.
With just one upgrade, you’d get something like in the video, but not sure what the “Get Upgrade Progress” values are for the first and second level.
I’m gonna leave the division by 100 out since it doesn’t change anything. If level 1 was 1000 and level 2 was 10000, then TargetHealth will still be at 1000 after the upgrade. That’s 10% of 10000. So the health bar will go down.
Like I said, I don’t know what the level values are. I also don’t know why it went down to zero. It’s as if the levels kept going up, but GrowHealthBar was only called once. Then this would cause the range to increase to almost infinity. So it’s not actually going to zero, it just looks that way because the max is getting really large. Do you have a timer you forgot to remove the loop checkbox or something?
I’d print a message every time the level goes up. Can we see the upgrade code or BP? What’s the level values?