I'm playing on FTB Horizons and although I haven't updated the Astral sorcery yet (playing on 1.7) I haven't seen information about this glitch in the patch notes. I am not exactly sure which mod added Multi-jump but I think it was Cyclic.
Anyway, I've noticed that if I fly greater distances my hitbox exceeds my player model and so I found myself hitting a wall thousand of blocks away. I didn't know what happened at first because I suddenly died mid-air and just got a message about experiencing kinetic energy on the death screen but then my grave note gave me coordinates that were really far away from where I actually died. I tested it two more times and it does seem that the longer I fly the further difference between my screen and my hitbox is.

I did not experience any of those issues when using vanilla Elytra

Also going to ask for the server log before and after it happens to see if it realizes there's desync.

I cannot replicate it in the updated single player because mantle doesn't seem to trigger. I've seen few people have a similar issue but haven't seen any solution. Basically, I jerk up and down while falling down when I try to use the mantle. It seems like Elytra mode switches between on and off rapidly when I am falling and holding the spacebar.

Not sure when the server will be updated, unfortunately.

https://pastebin.com/PLJbh1bT - server log

https://imgur.com/a/eYWGX screenshots of this test, not sure if useful

If you yank Roots2, Can you still replicate? Server log again if so. I have a curious.

https://pastebin.com/gh741LrQ You will need to scroll through a lot of deleted deers but the glitch still happens. As I said earlier, there are no issues when using the Elytra with the same method

Doesn't change that its a client/server desync issue, that the mantle invokes the elytra methods themselves, or that in each instance there's been worldgen cascades preceeding the impact-related-desync-death.

I'll leave the rest of this to Hellfire to see if there's anything he can do on this.

Can you make a backup of your world, update AS to the latest, and test again?

This issue mostly comes from a server-client desync due to some lag yea... idk how i would go about adressing this... The elytra is prone to this as it doesn't 'constantly accelerate' as the vicio mantle does... Additionally, the vicio mantle doesn't listen to some things like the vanilla elytra - which kicks you out of flight if you hit a wall (your horizontal velocity radically decreasing, more or less) - for the sake of a more consistent flight as it's been designed to do with the mantle...

It seems like Elytra mode switches between on and off rapidly when I am falling and holding the spacebar.

This was due to a ASM patch that doesn't apply itself properly. That should be adressed as of 1.8.X upwards.

@wierzejs can you confirm if this is still present in the 1.8.4 release following several changes made?

I'm setting up a modpack and I'm having the same issue of the mantle of stars (vicio) just causing rapid stutter while falling, rather than actually flying. Using Astral Sorcery 1.12.2-1.8.4 on forge build 2587. The issue was also present in AstralSorcery 1.12.2-1.8.3 on forge build 2555. Not sure what logs you'd need for that, but I'm happy to provide whatever you need.

Server logs from when this is happening, please.

@wierzejs @Kira076 Does this still occur in 1.8.5? We've not received any more recent complaints outside of you two. Need server logs from when it's happening if so.