Hi Huertaaj,
That fact that MG SAG worked before with S1 v6 is usually telling that either your new install, over v6, or started a new song folder, or had to install MS SAG over again worked, but the actual path to what caused your crashes is not yet clear. In short, you could try going to the plugin manager in Studio One, delete and run it again by searching plugins over again (often works). Or reinstalling MG SAG with a full reinstall. There's not a lot to go by on our end and while I'm not familiar with Soft Acoustic Guitar, I use a few similar acoustic guitar libraries including my own self made ones for Sample One. I've never encountered an issue, nor hear of many. Another consideration is when something like your issue occurs, it's a good idea to check your PC for available HD space, relocated libraries, latest drivers or any such things that cause the dreaded term "crash".
It's one of those check resources first, dismantle a little of what you last installed to regroup stability, and check as you proceed adding those few plugins or instruments back. Potentially, return prior to a recent OS update, etc.
Personally, I think you likely need to contact support so they can observe the issue better than our guessing (at this time).
Please post your specs for future inquiries in your sig (PC, CPU, platform, version, audio interface). This will avoid many preliminary question as to what you're using as we have no idea. TY.