Ay so Rush is a pretty good skill But say if I'm partying with someone and I Rush Bigfoot 3 feet towards a wall - it's really disconcerting seeing him slingshot back to his original position after a second or so due to my party member's client registering hits (at the old location) after my Rush knockback has finished. This happens frequently with corsairs or nightlords using their multihit attacks, and while it's a minor gripe, I was wondering if there was any way to prevent this sort of thing from happening. I figure this is just how the game's coded, buuuuuuut worth a shot
It's probably an issue due to his iframes typically always happens when you have multiple attackers even without rush. I would suggest just soloing a bigfoot rather than having to deal with other attackers as they can just make things longer and more difficult.
No, it's not an issue with Bigfoot; this happens with literally any mob that can be moved. I'm quite sure the OP has the right assumption, that it happens when the hit-stun of one client is prioritized over another in the server connection. You can't move mobs with Rush when they're in the hit-stun of another move. So when you're trying to Rush something in the situation of others attacking, the difference in connections to the server can give conflicting scenarios of where the mob should be placed. One where you successfully pushed the enemy with Rush, and the other's client where the mob was hit-stunned during that moment, so the mob must stay where it was. The server must choose one mob placement over the other, which is more likely to side with the mob not being pushed if we're dealing with fast multi-hit moves. On the client of the person with Rush, you get the visual the OP explained; you do push the mob, but then the server quickly updates it's position back to where it was because it prioritized the other person's hit-stun. That said, I don't think there'd be an easy fix for this. I have to deal with it a lot more often myself from having slow internet.
Same thing also occurs with Bucc Corkscrew Blow; can be very tedious to pin a BF with a BM/NL partner.