Does Horde breaker work with crossbows?

Question

I'm curious about the interaction between the crossbow's Loading property and the hunter ranger's Horde Breaker class feature. Specifically, can a hunter ranger wielding a crossbow use the Horde Breaker feature to fire a second shot after they make an attack (using the Attack action)?

What makes me curious about this is that the wording of Horde Breaker just specifies that you make a second attack, without specifying how this fits into the action economy: is it part of the Attack action, or is it an attack you can make not as part of any action? This answer seems to suggest that Horde Breaker occurs outside the usual action economy, but this seems surprising to me. For reference, the rules text for the two abilities is below (emphasis mine).

Horde Breaker: Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon.

Loading: Because of the time required to load this weapon, you can fire only one piece of Ammunition from it when you use an action, Bonus Action, or Reaction to fire it, regardless of the number of attacks you can normally make.

Answer 1

The loading property is ignored because the attack from Horde Breaker is not part of the Attack action

Features that grant additional attacks that are part of the Attack action explicitly state this (the examples I'll use are Extra Attack, the Samurai Fighter's Rapid Strike feature, and the Gloom Stalker Ranger's Stalker's Flurry feature; the emphasis is mine):

Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.

If you take the Attack action on your turn and have advantage on an attack roll against one of the targets, you can forgo the advantage for that roll to make an additional weapon attack against that target, as part of the same action. You can do so no more than once per turn.

At 11th level, you learn to attack with such unexpected speed that you can turn a miss into another strike. Once on each of your turns when you miss with a weapon attack, you can make another weapon attack as part of the same action.

Because the Horde Breaker features does not state that it is part of the Attack action, it is not part of the Attack action and so it is not subject to the Loading property.

The Loading property only applies when you use your action, bonus action, or reaction to fire the weapon; here you are not using any of those. Is it clear that you are not using your bonus action or reaction as these would be explicitly stated as being required, and by comparison to other similar features, it is also clear that this attack is not part of the Attack action.

Answer 2

Yes but the case is unusual

The Loading property states (emphasis added):

you can fire only one piece of ammunition from it when you use an action, bonus action, or reaction to fire it

Since Horde Breaker does not use an Action, Bonus Action, or Reaction the Loading property does not apply.

This is an unusual case, however, because extra-attacks are nearly always predicated on the use of an Action, Bonus Action, or Reaction. Consider the Gloomstalker's Dread Ambusher feature which reads:

If you take the Attack action on that turn, you can make one additional weapon attack as part of that action.

Since the additional attack is part of that action it would be incompatible with Loading weapons.