As seen in https://clips.twitch.tv/ResoluteElatedOysterWTRuck arrows sometimes pass through mobs without harming them.
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Not sure if that relates since the projectiles spawned several blocks away.

Can confirm in 21w05b. Haven't seen it yet in 21w06a, but that's not to say it's fixed.

Major bug for pvp and pve, refered to by most players that experience it as "Ghost Arrows".

This also happens with any projectiles, not just arrows.

Maybe this should be renamed to "Projectiles sometimes go through mobs" or something similar.

Reiterating: major bug for combat, and I believe this should be more prioritized.
Can confirm this in 1.18.

Since netherite knockback rng was fixed for 1.18.2, would be nice to see the other major PvP bug fixed for 1.18.2 as well (this one).

So I figured out what's actually happening here, and the bug should be renamed to better reflect it. When this bug occurs, the projectile is completely fake. It has nothing to do with the projectile not hitting mobs, when this bug happens the projectile doesn't exist at all. It can happen with ender pearls during combat, where you throw it, watch it, and when it lands nothing happens. Bug is similar to the old ghost buckets bug but with projectiles. Report should be renamed to reflect this.

Also requesting ownership as the OP is no longer updating affected versions.
@PotholedSea40 I assume by "not existing", you mean that the projectile appears on the client, but the server doesn't recognise it as an entity and therefore doesn't update it. I don't think that's the issue as this bug also happens on Spigot servers and I have been able to "patch" and detect this bug through a plugin by doing my own raytracing. This suggests that the projectile does exist on the server, and even though I am using Spigot, it's highly unlikely that there would be two different causes for the exact same bug. It seems as though internally, the projectile's collision isn't being detected by the server, which means that even Spigot isn't aware of the collision (as the ProjectileHitEvent doesn't fire automatically), however I don't know enough about Spigot's architecture to make any conclusions here.
Either way, I don't think those observations are enough to definitively rule out any other possibility, although there is a very simple test you can do to confirm your theory. Setup a repeating command block that runs the following command.
execute if entity @e[type=snowball] run say hi
Then spam snowballs at an entity one at a time until the bug is observed. If the projectile still clips through entities despite being detected by the command, then it exists.

I assumed that updating affected versions was a thing the mods did, as the only update I posted was the snapshot version, and mods would update when someone confirmed the bug for a new version as happens with many other bugs. If you want versions added, just do what Avoma and co have done, as I have a job (and playtest other games in my freetime) and can't always confirm it exists on new versions (especially since I've encountered the bug three to four times ever when I do test for it. I suppose I could write a bot to shoot the bow for me and then detect when the arrow doesn't collided with the mob after a certain amount of time to test on eash version, though,

Keep in mind that your experience isn't everyone's, just because you yourself haven't run into a bug a lot doesn't mean it doesn't effect others much more. The reason I highlighted this one specifically is because it's such a major issue for PvP, and can feel extremely unfair when it happens (which is very often on combat servers).

By focusing on one thing trying to usurp a freaking bug report from someone instead of commenting what versions are currently affected and aren't listed, all you are doing is wasting everyone's time.
As I said in my previous post, which you failed to read:
Do what Avoma has done and post versions you can confirm this bug on, and it will be added to the report. Otherwise you are creating unnecessary drama.

Mate chill, I simply asked and gave a reasoning, this isn't some crazy occurence on this site nor should you being taking immense offense to it. Can confirm in 22w15a.

Finally, some useful info.
Adding it to the list.

This bug likely happens because in one tick, the projectile is in front of the mob, and in the next tick, it is behind, never making contact. a way of fixing this would be to add a raytraced check to see if the projectile's path intersected a mob's hitbox.

Again I don't think this is the case because you can't pick up ghost arrows (which is why I made the claim that they are purely visual). I'm actually not 100% sure if the projectile shot/thrown that ghosts through stuff disappears from your inventory or not.
@Torzod Minecraft is definitely doing raytracing; if it didn't, then this bug would be significantly more prominent. You could test this yourself by summoning a super fast arrow and observing that the projectile still collides with mobs even though the projectile may have otherwise flown straight through the mob.
@PotholedSea40 It's possible that the projectile simply isn't colliding with anything (even blocks), and there might be some client-side code that handles animations and particles for collisions with blocks. That's not to say that the projectile doesn't exist on the server (see my previous comment), however a way to check this could be to see whether the same projectile clips through multiple mobs when the bug occurs. That would test whether the bug is a property of the projectile, or of the collision.

confirming and updating for 1.19 pre release 1

Can confirm in 1.19 pre release 5

Can confirm in 1.19.1 rc1

Can confirm in 1.19.1-pre5

Can confirm in 1.19.2

Can confirm in 22w44a.
Can confirm this in 1.19.3.

Can confirm in 23w03a.

I'm locked out of my microsoft account, but if someone could, it might be helpful to see exactly how far back this goes so that Mojang can narrow down exactly what changes might have started causing this.

Judging from when I first made a bug report video of this happening, I believe this issue first appeared in 1.16. It could have been a bit before then in 1.15, but I can 100% guarantee that it didn't pop up any later than 1.16, and I'm 99% sure it wasn't an issue before 1.15.

Can confirm in 23w06a.

Can confirm in 1.19.4-pre3

Can confirm in 23w12a

Can confirm in 23w18a.

Can confirm in 1.20 release canidate 1

Can confirm in 1.20.1

Can confirm in 23w31a.

Can confirm in 23w32a.

Can confirm in 1.20.2

Can confirm in 1.14, took 3 weeks of monitoring a slow-fired creeper farm built exclusively for testing for this to find, but can be repeated fairly easily once it does, not sure why

Can confirm in 23w40a.

In 23w43a.

can confirm in 1.20.4

Can confirm in 24w06a, affects wind charges

Confirmed in 24w07a

Can confirm in 1.20.5-pre1

{*}{*}Can confirm in 1.20.5 & 1.20.6-rc1

Can confirm in 1.20.6 and 24w20a

can confirm in 1.21 through to 1.21.4
interestingly - in 1.21.2+ when this bug occurs, the game summons a "ghost arrow entity" where the arrow appears to bounce off the entity it ghosts through, but then the actual arrow entity reappear to have landed where it should be
Relates to MC-125936