The problem that I see is that everyone wants to make the "Invisible" condition mean more than it does. Invisible means you cannot be seen, attacks against you have disadvantage and you cannot be targeted by LOS spells. That's it. The enemy knows what square you are in. You aren't hidden (in the plain English sense of the word) when you are invisible.
If you want the baddies to not know where you are, you need to take the hide action. At that point, they have no idea where you are (presuming you succeed).
At least, that's how I interpret the rules.