Toggle Visibility Doesn't Work on Player Character

I tried Set Actor Hidden in the Game, too, but it didn’t work, either. Is there a node to make the character unvisible for like 0.5 seconds?

Hello,
set actor hidden in game works fine so you may have change something in your character which does the trouble (or it can be a bug if for example you converted project to new engine version)

If this is not the node, this how you use it.
Try a set actor hidden in game in defaults , to see what happens.
Then use the node on “event begin play”. to see if it works in your project.

From there you can see if the trouble is from your project or the way you use the node to hide.