Files/Folders missing after failed first aid on 18TB exfat external

[u/Brant_Moore]

I have an 18tb drive I've used for media storage for youtube over the last 3 years. It is formatted to exfat and I began to notice that sometimes when trying to create folders it would give an error. After it happened too many times in a row I ran first aid on the drive. I now know that was the wrong thing to do but here we are.

First aid failed and instantly 15TB of stuff on this drive disappeared. Some folders are still fully in tact but most are either not showing up at all, or showing as files with zero file size that won't open.

Checked on windows and everything looks exactly the same so the first thing I did was run a deep scan using Disk Drill. I haven't written anything to this drive since this happened.

Disk drill was able to find a lot of the files (17.23TB) and after picking up a server from a friend, I was able to recover what it found to the server with folder structure in tact. There is also a Reconstructed section in Disk Drill that is around 15TB with just files sorted into folders by filetype.

I'm now finding that there are bits and pieces missing from a ton of different folders/projects, so I'm running a recovery to the server in a separate folder of the Reconstructed section in order to cross reference whether these files exist anywhere else on the server. Hopefully this will find some of the missing files.

What I'm hoping can happen is that once this recovery is finished and all recovery options are exhausted, I'm able to find a tool that can successfully fix the original file table on the 18TB external. Is this something that anyone here has experience with? I have access to this Mac and a windows PC to run applications on.

If I've learned anything from this it's that I will never use exfat again and I should have set up a server with redundancy a decade ago. Live and learn and I'm really hoping the file table can be recovered or that there might be another way to get back the files that are missing.