I've been testing a bunch of armor, making armor that has different attributes so that you can have armor that's just as powerful as diamond armor, without it being diamond. Other custom armor things, like adding speed to see if that made a difference. I've tested on multiple of my servers, a spigot 1.13.2, spigot 1.14.3, spigot 1.14.4, and then just a Vanilla 1.14.4. None of them allow this to work. I tested this on a Singleplayer world, 1.14.3 and 1.14.4 and it works perfectly fine. The bug here is that when you put on a custom attribute piece of armor, it adds whatever you have, health, armor, etc. but when you put on another, if the attribute value is less, it won't do anything, and if it's more than the first one, it will replace the first one's value but not add onto it. This might be a little confusing, but imagine leather armor that has the attribute of diamond armor, and they each add an extra heart of health too. When you put the first one on, it works fine. When you put the next piece on, it will only give the player the attributes of the second armor. Putting the helmet on first, they'd have 3 armor points, and then the extra heart. When you put the chestplate on next, it changes their armor points to 8 and they still only have the one extra heart. Removing the helmet does nothing at this point (because it has all smaller or equal values to the chestplate) but removing the chestplate will take away all of the players armor points and extra health. This is a major bug for me as I'm trying to work on custom armor plugins, but I would appreciate it if you could fix this. Thank you for taking the time to read this.