multiplayer - How to predict movement correctly when a player is invisible?

I have a multiplayer game and I'm doing client-side prediction, but some players can drink a potion and become invisible...

The problem is that when they become invisible I don't share anything that the client could use to know he's there, so when a player tries to step into a tile occupied by a invisible player, he predicts that he succeeds, and then gets a ugly position correction sent by the server.

One solution would be to share something so the client can tell, but then hackers could use it to find out where invisible players are, cheating.

Btw I already solved regular movement prediction, it works perfectly.