Latest Windows 10 version of Minecraft, downloaded from the Microsoft store.  There's an issue when connecting to Mineplex.

When clicking  on Play, Servers, Mineplex, Join Server

It says "Could not connect: Outdated server!"

It's been like this for 3 days now.

The other servers available work fine - Mineville, Cubecraft, Galaxite, The Hive, Lifeboat.

Edit - I have reported this to Mineplex, 2 days ago, but have heard nothing back, yet.