As stated by others, Plunder doesn't end. You can still access the menu at any time, you just can't plunder if there is no convoys going. So waiting till after convoy ends does nothing for you if someone is still waiting to plunder.

Secondly, by waiting to do the same thing every day, you've let everyone know exactly when you will run. They know you have to run within 30 minutes of closing, so they can just wait. And since they know you do it everyday, you are an easy target. If you cannot get a strong enough support to protect you, you should try to vary when you run so people don't notice the pattern. You c*so run with other people at the same time, assuming it's a time when there isn't too many plunderers waiting. If you run with a group of last minute guys it might help you escape since there are so many other targets.

Hi there!

Keep in mind that plunder has requirements which can be seen in the attachment below. Also, there is a 15 lvl cap requirement between the plunderer and the one doing the convoy. If you are trying to plunder a player with much less than 15 levels from your current level, then the system won't show any active convoy on your perspective. It has always been this way and I don't think they will change it for the reasons stated above by the others. If you meet all of these criteria and still not being able to plunder then you might be experiencing a bug.

Ex: A level 86 can plunder a lvl 71, but convoys of lvl70 and below he can't see in the plunder interface thus not letting him to plunder. Point is, plunder is always open :)

Hope this helps!