Mainstage 3: No Plug-ins / Cannot create new concert

Hey all,

A few months back I tried to download some additional instruments, but could never figure out how to get them working in Mainstage 3 (just the app, not Logic Pro). Basically, I gave up and just worked with what I had. Fast forward to last night, a bit of curiosity took me and I tried to figure out the problem. However, now I am even more confused. Here is what I know:

- I have a few concerts already made and they work and can be edited/saved.

- The plug-ins are installed in the correct area (/Library/Audio/Plug-Ins/Components) and there are 3 in there: Synth1, U-NO-62, and Da Hornet. They're all free, and downloaded via the internet. Not sure if that is relevant, but I figured I should explain everything I know.

- I cannot find the plug-ins anywhere in Mainstage.

- The plug-ins work fine in Garageband.

- I just updated everything on the computer last night (including a Mainstage update) and I'm still having the problem.

- And as of last night, I found that I cannot create any new concerts. I checked under "File" and the new concert button is grayed out. Pressing Command + N just makes the computer flash quickly.

- I cannot delete any concerts via the Mainstage window. I have to go into Finder and delete the file from there.

I'm not sure if these two things are related or not. I haven't made a new concert since before I tried to install the plug-ins, so they could've happened at different times or at the same time. I feel like I'm missing something obvious, and I can't seem to find anything on the subject anywhere.

Thanks!