Icons in window rendered way too big. (Unity, RoboMongo)

I have a weird problem and no idea what could have caused it. I installed Robomongo on my Ubuntu 16.04 machine a few months ago and it worked just fine back then, but now I've started it for the first time in months, and suddenly there are rendering issues. Functionality-wise it still works; it's just the UI that is messed up.

Here are some screenshots:

Does anyone of you know how I could fix this?

I haven't experienced any issues like this in other applications.

Edit: I just reinstalled robomongo and switched from 0.9 to 1.0. I'm still experiencing the exact same issues. I also tried to run it with sudo just to see if it makes any difference, but nope. And there is no output when I run it from the terminal.