After I had largely edited the progression config in-game, in singleplayer, after restarting the modpack and trying to open the GUI again it immediately closes down minecraft. Something that I also noticed is that it also leaves the process still running in the background.

I run with this modpack on the technic launcher: http://www.technicpack.net/modpack/mcdestiny-20.720894

I have tested putting it on a server, worked without a problem. Though as soon as a client tries to open the gui on the server, the client crashes.

I run Windows 10, with Java 8 and forge version 1448. I have a more than enough powerful computer to run things like this.

You can get the logs and criteria.json files from here.

If you could fix and/or tell me what is causing it to crash, it would be very much appreciated. But until then, I'm going to drop progression.

Yeah progression was very unstable in 1.7.10, for me it was a very experimental mod, I've learnt a few things from it, and am working on improving things in the 1.8.9 version.