Logic Pro X - All plugins missing

Hi,

I recently booted up Logic Pro X for the first time in a while. I recorded some audio, and went to start adding some effects and found that all my plugins are greyed out; it says they're missing. What's bizarre is that if I choose a preset set of effects (e.g. the Lead vocal one that applies compression, reverb etc), most of them are there. But if I try and modify them or use them in another channel or slot, they say they are missing.

I haven't changed anything on my laptop or logic. I'm on OSX 10.13.6 (MB Pro 2011) but it always worked fine previously.

Anyone know how I can fix this?! Really frustrated!