When does a hidden opponent that is moving become visible?

Question

Directly inspired by the question, When does a hidden opponent that is attacking become visible?.

From the Player's Handbook, page 194:

If you are hidden -- both unseen and unheard -- when you make an attack, you give away your location when the attack hits or misses.

I realize that there is not much information on how movement is supposed to play a part, if attacking while hidden is regularly possible.

Take a scenario with a Rogue hiding behind a building. He has all line of sight blocked from all enemies at the moment, who know that he's behind the building but not sure exactly where. He has the Skulker and Crossbow Expert feats. He pops out from the corner of the building, attacks, and he misses.

1. In order to make that attack, he popped out from the corner, and must have been within the enemies' line of sight. Is he no longer hidden, despite having the Skulker feat?

2. If he is still hidden after his first attack, can he move 15 feet into the open and make a second attack as if he was hidden?

3. Lastly, if he misses with the second attack, and attempts to move back into cover, is he no longer hidden?

When in this sequence is the Rogue no longer hidden?

Answer 1

You can attack from behind cover. Moving out of cover reveals you.

Research into this question has resulted in me finding my own answer!

From this Sage Advice link (found from this answer to a question about repeatedly hiding in combat to Sneak Attack the same enemy), I found a complete explanation.

Here is a conversation between Lead 5E Designer Jeremy Crawford, and a concerned player:

I am curious: when the rogue starts round hidden behind wall, moves out, attacks... is she hidden during the attack? Or, broke cover and no?

Are you referring to an attack from behind cover, or are you referring to a rogue who moves X ft. in the open and then attacks?

Later. Rogue starts hidden, moves out to see foe, attacks. Players like to argue they are still hidden on attack.

You can attack while hidden and gain the benefit. But if you run out into the open and then attack, you're not hidden when you attack.

Here, Crawford states that it is possible to attack while Hidden to gain benefits. However, if you move out of cover, you are "not hidden when you attack", so it's implied that you're no longer hidden as soon as you move.

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my main problem is can a rogue attack with advantage thanks to hiding.

Yes.

say if the rogue has to come from behind corner/tree/cover to get a line of sight, that's ok?

Yes.

Here, Crawford confirms that moving from behind cover isn't enough to break the Hidden condition, as opposed to the earlier example of moving completely into the open.

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[...]

So shooting a bow while hidden maybe grant the advantage, but running out in melee dont, does that sound about right?

It does!

This last piece indicates that ranged combat inherently has the option of "popping" out of cover to attack, which does not create enough line of sight from an enemy to reveal your location. Melee combat will generally require movement, so it doesn't have this opportunity.

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Summary

Moving out of cover will cause you to no longer be hidden. However, you can make ranged attacks from behind cover without risking your position (assuming you have the Skulker feat) and without ever leaving cover.

This indicates that the character in the example scenario would be hidden for #1, but would be spotted as soon as he moved out of cover for #2.