Weird Selection Box in UE4.17.1 (macOS)

Hello, I’ve just started using UE4 on macOS. It looks to be a very powerful tool, but I have one bug/glitch which I don’t know how to fix it. It’s quite weird, the selection box is kinda pixel-style. It looks like it’s a retro game from the 90’s. It’s not a huge Problem, but it’s kinda annoying. Does anyone of you guys know a solution to this problem?
I don’t want answers, which are like: “It’s not a big problem at all” or something similar to that.
What is most annoying about it, is that you can’t see the blocks in front of it.