Item Guard Expiration Glitch

Eh, firstly, using the MTS to nx into mesos is the easiest way of going about things since you have a risk of getting scammed trading them directly.

And secondly, why does anyone care about these NX for mesos trading people. The only difference between them doing that and using the MTS is that nexon misses out on some tax. It's not like they're doing something that hasn't already been designed into the game by nexon themselves. Even if he did directly trade through rather than using the MTS the outcome is exactly the same for everyone except nexon, and honestly I can't say I'm too sad about them missing out on a little tax after hearing about stuff like this

Regardless of any of that, they owe it to the players to fix this ASAP since this was caused by their own CS item that people payed for to ensure something like this would never happen.

Also, just curious, what happens if people try to re-lock the items with another lock from the cash shop?

I don't think you can lock items that have an expiration date. If you could, there would be a lot of abuse.