I think this is a easy one to fix☺.I wanted to scroll to see my rewards in the chat box in Mineplex but I couldn't. This is also a problem in regular gameplay.I think this can be fixed by using the right stick on the controller☺.I know the left stick is used for selecting through typing bar, command button and keyboard button same with the D pad. But the right stick dose nothing. ☺So I say it
should be used for scrolling through chat.

Here's some help for reporting bugs in mineplex look in the picture below in the blue highlight. For their website.