This is most important part the 1st part you just wrote
Look you had before HP MAX at 200
You add 30 to your HP MAX when you get health potion
And you get -30 HP or HP MAX whatever
What is important here
You changed HP MAX from 200 to 240
And instead of adding 30 you are adding 50
So now it should give you either -50 or -10 but not again -30
Which means what you just changed have ABSOLUTELLY NO effect for what is causing it
I would suspect you have somewhere event that is setting HP to -30
Cause there is no other way to explain it
Because there is NO WAY for it to still be -30 AFTER you changed max hp value and for how much max hp you get after you pick up health item
About what you don’t understand
This is less important but it can actually fix stuff
Or more like let you bypass your bug while not fixing it
You have action here
Change variable HP MAX add 30
Delete Health
I ask you to add there one more variable change but for HP var
Change variable HP MAX add 30
Change variable HP add 30
Delete Health