Basically there's a problem where advancements added through things like Datapacks, Server code such as Spigot/Plugins or whatever other ways if it's not the vanilla ones and the size requires the window to be moved around it will glitch and move up and down repeatedly and not show the actual rest of the area to reveal the out of frame advancements but again it still works in the vanilla menu.

Here is an example of me trying to navigate a custom advancements menu and it glitching out: https://giphy.com/gifs/j0paIn1wbt9vOncSPv

Updated to add datapack showing same problem, this is in a vanilla environment.