Unreal 4.24.3 acting a bit weird

Hi, I’ve spent a few weeks doing a diorama for a uni project. I’m on a mac running os catalina.
A few days ago when i opened the project “Hotel” a lot of my normal maps and materials were missing. But all the assets seemed to be there.
But the lighting didn’t look quite right.
So I duplicated the project now called “Hotel Copy” and all the materials and everything seemed to be there and it was back to it’s appropriate state.
I worked on Hotel Copy the last couple of days and yesterday, saved it and shut down my mac.
This morning I opened Hotel Copy and all the assets were gone and the folders from the Content Browser. Most of the materials and textures were gone as well.
I duplicated this to Hotel Copy 2 and then Hotel Copy 3 and did some other random things like try and delete the intermediate folder but everything was gone.

I then thought i’ll see what is in the original “Hotel” project I hadn’t opened for days and weirdly everything I had been working on from the last few days in the “Hotel Copy” project had found it’s way to the original “Hotel” project. Or i’m going a bit crazy but i think that’s what happened.

It’s not really a bug but just concerned for future projects that this might happen again.
Before this all started I had moved the folder on my mac containing all the fbx files and textures to a portable hard drive because of space issues. I have about 20gb left on my mac. But I didn’t think moving files would cause issues because i didn’t think UE would be referencing them still.

I also installed UE 4.25 earlier in the week and have been trying to set it up to use with an oculus quest headset. But didn’t really think this would be the cause of the problem.

I didn’t know where to post this so admin feel free to delete.