AFAIK, you can’t apply physics impulses to characters the same way you might do it for a crate. Are you using a “Character” pawn? They have a “LaunchCharacter” function that might do what you want.
I’d like to have physics on my character so that if another actor with physics bumps into it, my character will move. (Or push it down when in a water volume).
I set “Enable Physics interaction” to true, and I can push other objects, but the other objects can’t push me.
If I set “enable physics simulation” on my character root component, I won’t be able to move it anymore.
Am I missing something ?
I spent some time researching how to apply an impulse to a character, and LaunchCharacter was the best thing I found on the internet 
I use it when my character gets hit by projectiles, for example.
Yes I am using a ACharacter pawn, using LaunchCharacter would be weird I think ? I could use this with onComponentHit but then the Actor that bumped into my character will stop moving.