Some problems:
Anti cheat has caused some major problems. Aside from causing elytra to not work, it is now impossible to pillar up. Attempting to pillar up more than 2 blocks will cause you to get stuck in blocks or your blocks to vanish. Other issues are caused by some kind of weird lag, the server has been stuck at around 5 tps all day causing players to be unable to eat and unable to ender pearl effectively. I've also noticed a few instances of some rubber banding (getting teleported back a few blocks, but this only happened a few times).
I think an immediate solution would be to remove anti cheat entirely. We dont have enough new guests to worry about them flying, and it is easy to spot them when they do. Anti cheat has neutered the functionality of slime blocks and it is now ruining elytra. Removing anti cheat would fix the block lag / pillaring issues.
Aside from the issues the update is smooth every where else, thanks for the fast update!
Update: It appears the server restart fixed all the lag issues. The only issues that remain can be solved by removing anti cheat.