Upgraded to Yosemite, lost all sound fonts

I recently upgraded my OS from Mavericks to Yosemite. Everything was going well-ish after the upgrade (generally slower than Mavericks, which is annoying) until I noticed that some instruments weren't making a sound in a Garageband composition. Turns out my sound banks (Library > Audio > Sounds > Banks), where my sound fonts are stored, are now empty. I've checked both Libraries, under Macintosh HD and "User", but no sign of them. I've searched using Spotlight and they're nowhere to be found.

This is pretty frustrating as I've spent a long time gathering sound fonts for use on various projects, but they've all been removed in one fell swoop. Thanks Yosemite.

Anybody else come across this? Am I just unlucky? I'm hoping this is the only chunk of files to go missing after the upgrade! I guess time will tell.

If you're thinking about updating, copy your sound banks folder to a safe location first!