CollisionGroup = Default, CollisionFidelity = PreciseConvexDecomposition and Locked = false yet I still cannot select any. If it makes a difference, They are really big meshes.This is an example of how big the meshes are. All of the seats/walls in this screenshot are meshes that cannot be selected.
Can you find it in explorer and select meshes through it?
Yes but there are loads of them so it is very hard to do. At the moment I have just been using a part selector plugin to find the name of it and then search it up in explorer but that is not a long term solution.
Make sure the meshes aren’t locked.
They aren’t, All of them are unlocked.
Have you tried to reopen/reinstall studio?
Reopen, Yes. Reinstall, No. But this has never happened before and studio hasn’t updated recently for me so I don’t know why. I will try and reinstall though now that you say it.
This is why you need organized naming schemes, super important. Although I am personally a victim of cluttered workspaces as well, having nice organization can be super helpful with larger maps. Let’s say you name every seat “Seat” and every wall “Wall”, and different types maybe different names. You could then just filter the name in the explorer and ctrl+a to select all of them, boom! (and if you have really really large amounts of stuff in workspace just use folders)
Anyways for current solutions you could try and select one property EVERY seat has, like color or a tag or anchored or I don’t know. Select everything in the explorer (ctrl+a) that has said filter, and that should be it. If you have like more items that have the same property you can deselect them if there aren’t too many.
Not sure if this gives you the solution you need but at least hopefully you learned something idk 
I have a very complex folder organization but there is one thing. Everything is in workspace and not in the folders 
What is the CollisionGroup of those meshes?
Check this post. It may help you.
It’s not that. As I have said, The collision group on everything is set to default. I honestly don’t know what it is at this point that is causing it.
Everything is custom named and in folders.
Then why is this not a viable solution (or using name)? Use explorer filters.
Make sure no GUI are blocking by disabling UI Visibility
There are no GUIs in the game.
